This is necessary to facilitate the transition to cloning attributes instead of reparsing them.
MozReview-Commit-ID: Gyd1tD6ldly
--HG--
extra : rebase_source : 777cfed750c95c448f953a6ec98026481997e227
In order to facilitate the movement of code with side-effects called by Element::SetAttr to Element::BeforeSetAttr and Element::AfterSetAttr, Element::AfterSetAttr should have access to the old value of the attribute. This includes information about whether there was previously a value set or not.
Accomplishing this involved passing an additional argument through functions that find and change the old attribute value in order to ensure that we can differentiate between an empty old value and an absent old value (attribute was not set).
Note that while I tried to ensure that accurate values (and their absence) are reported to Element::AfterSetAttr, I largely ignored SVG. While the old value reported for SVG values should be however accurate the value already being reported to SetAttrAndNotify was, SVG elements do not currently report unset values properly because they will never pass a null pointer to SetAttrAndNotify.
MozReview-Commit-ID: K1mha8CNFZP
--HG--
extra : rebase_source : 42776eb01451d371e4aebcc17fe3dd112c8d268b
Defer determining whether we have usable decoders to an off-main thread in
order to avoid janking the main thread.
MozReview-Commit-ID: Ape5zEBBMrz
--HG--
extra : rebase_source : 1b77046ebb7bb2d4ff1ba53afce904d3de45c335
Currently, attribute and child arrays (implemented in dom/base/nsAttrAndChildArray.h) start out empty. When cloning, the array ends up being resized multiple times in order to add the attributes and children that are being cloned from the original node. This would be quicker if the array was initialized to the correct size in the first place so that resizes are not necessary.
However, preallocating space for children is only necessary when performing a deep clone. Therefore, an additional parameter is being added to the Clone, CopyInnerTo, and CloneDocHelper methods to indicate whether preallocation of children should happen. Attributes are copied either way, so that part of the array is preallocated in both cases.
MozReview-Commit-ID: 3iVezeAKXnI
--HG--
extra : rebase_source : 9c3deec6d7aafd6411044d623d4863637b45fd58
There was a cycle amoung a window object -> a HTMLMediaElement -> a MediaDecoder -> a Promise (-> back to the window object).
And we have no way to break the cycle since the MediaDecoder does not participate into the collection.
By moving the Promise form MediaDecoder to HTMLMediaElement, we will be able to break the cycle since the HTMLMediaElement is in the collection.
We'll implement the cycle collection in the next patch.
MozReview-Commit-ID: CyVXBl6IMI3
--HG--
extra : rebase_source : 195a322ce3e6fe933e72be4aec5d2ebfa1f54865
This mMediaTracksConstructed flag should belong to a MediaDecoder,
every time a HTMLMediaElement switches its MediaDecoder, the flag should be reset to false again.
So, we move the mMediaTracksConstructed flag back to MediaDecoder, by this way,
HTMLMediaElement provides only the mechanism to construct and remove media tracks,
and MediaDecoder uses the flag, mMediaTracksConstructed, to provide policy.
MozReview-Commit-ID: L7mMAmLjQCy
--HG--
extra : rebase_source : 1625d604afb34bffe79eda06a46c9feb780a14d9
Move the creation of MediaElementGMPCrashHelper out from MediaDecoder.cpp
which reduces the dependency of MediaDecoder to HTMLMediaElement.
MozReview-Commit-ID: E60aMfcFr7V
--HG--
extra : rebase_source : f50a8ee6f2fbec0bdf117eb1217066bc9c701745
extra : source : dd4e52da6d0d6205fe61d0caba44bbff008fd21a
ConstructMediaTracks and RemoveMediaTracks are actually HTMLMediaElement's responsibilities.
MozReview-Commit-ID: 8lOdzD4pN7N
--HG--
extra : rebase_source : 7159d2c62b77429e5b2305b9e3eb7a0020a3b52c
extra : source : 0467c059be3cd8f066da5fc912b7738a5b9c4dd9
Open a GetOwnerDoc() method to the MediaDecoderOwner interface and then we can get the
owner document via a pointer to MediaDecoderOwner in MediaDecoder.
MozReview-Commit-ID: JCzQDLx1MsU
--HG--
extra : rebase_source : e194c95cb1513046ec7aa19d6c6e9f8231971a2d
extra : source : 1b9c45911a036e3677b6636cda84a636681d71de
Move all the policy rules into this method now, will then move the policies into MediaDecoder at next patch.
MozReview-Commit-ID: ILAYLrTwCJy
--HG--
extra : rebase_source : 8ae3adcbbd8f2fd61f0da0de437f41f78d945c89
extra : source : feb8ad754e86b43e15bf2eeb3a2ba2dc24a00599
Mark video element as tainted (stored on the decoder owned by video element) when the video is used as source to drawImage() on canvas.
MozReview-Commit-ID: HdciVwhqPu3
--HG--
extra : rebase_source : 79e1bbdc671abb8555d68f7fb6106929c45fd528
extra : intermediate-source : 47fbcedbed69a5434b1cb25b8f72f862e9cefeac
extra : source : 149234329b62015dfd2e954030c23bf9c6b1d55e
Mark video element as tainted (stored on the decoder owned by video element) when the video is used as source to drawImage() on canvas.
MozReview-Commit-ID: HdciVwhqPu3
--HG--
extra : rebase_source : b26c257afaaabdd6346a5421988d95e82281d7ef
extra : source : 149234329b62015dfd2e954030c23bf9c6b1d55e
Similar to DecodeError, except we allow decoding to continue.
MozReview-Commit-ID: FN9m03o6GXV
--HG--
extra : rebase_source : a6ca0cc28d2990ab143676758cd880baaca7bcb7
Dispatch |QueueLoadFromSourceTask| to main thread to make sure the task will be executed later than loadstart event. And when the src get errors, we need to end the synchronous section.
MozReview-Commit-ID: EQ0jVIMnqoZ
--HG--
extra : rebase_source : 876c62669f56581e903830beddbf0ce4435366e2
Dispatch |QueueLoadFromSourceTask| to main thread to make sure the task will be executed later than loadstart event. And when the src get errors, we need to end the synchronous section.
MozReview-Commit-ID: EQ0jVIMnqoZ
--HG--
extra : rebase_source : 6651826ad8de361deda5bdc0a49b2c68dcf86220
In this patch, the following utilities are implemented:
(1) A list to keep pending promises of a HTMLMediaElement.
(2) A method to take pending promises out from the HTMLMediaElement.
(3) A global function to resolve the passed promises.
(4) A global function to reject the passed promises with an error code.
(5) A method to asynchronously resolve all pending promises of a HTMLMediaElement.
(6) A method to asynchronously reject all pending promises of a HTMLMediaElement.
(7) A method to dispatch a 'playing' event and resolve all the pending play promises.
All the above functionalities are defined at WHATWG 4.8.12.8:
https://html.spec.whatwg.org/multipage/embedded-content.html#list-of-pending-play-promises
This patch also implements two MediaEvent classes, nsResolveOrRejectPendingPlayPromisesRunner and nsNotifyAboutPlayingRunner, which help (5), (6) and (7).
This patch also implements a list of already-dispatched nsResolveOrRejectPendingPlayPromisesRunner; we keep tracing these tasks because the load algorithm resolves/rejects all already-dispatched pending play promises (in patch 2).
MozReview-Commit-ID: EUirNqDfttk
--HG--
extra : rebase_source : e48196e77341926900747b3f9477c5ee9ed28f62
extra : intermediate-source : 9b349c0e9eedad8822a1b8e8ef375ac6cb0b635a
extra : source : 75ee3b084edb68709503c98ad7b72850af7bb9c8
UpdateAudioChannelPlayingState() should only be called when following attributes changed.
eg. pause/ready state/error/owner document's visibility/exteral source stream.
Therefore, we don't need to call this function in FinishDecoderSetup() and AddRemoveSelfReference().
Remove AutoNotifyAudioChannelAgent is because now we don't check HasAudio() for IsPlayingThroughTheAudioChannel().
MozReview-Commit-ID: 4VTHIAdAqX1
--HG--
extra : rebase_source : 5ee4cabd543fe43b4e51fa4ce68af083c8fd8e1a
In order to keep the media element's code clear (spec code only), we want to remove our
custom policy code out from media element. This new class will handle all audio channel
related stuffs, eg. mute/unmuted operation from tab audio indicator, play/resume from
Fennec's media control.
MozReview-Commit-ID: 5mDqDBTnBOr
--HG--
extra : rebase_source : cdb0a4b67c3e96bede79f61cc9d79b920517f139
UpdateAudioChannelPlayingState() should only be called when following attributes changed.
eg. pause/ready state/error/owner document's visibility/exteral source stream.
Therefore, we don't need to call this function in FinishDecoderSetup() and AddRemoveSelfReference().
Remove AutoNotifyAudioChannelAgent is because now we don't check HasAudio() for IsPlayingThroughTheAudioChannel().
MozReview-Commit-ID: 4VTHIAdAqX1
--HG--
extra : rebase_source : 7f196581fb2e5a7e75afef27d874522986d2cdc5
In order to keep the media element's code clear (spec code only), we want to remove our
custom policy code out from media element. This new class will handle all audio channel
related stuffs, eg. mute/unmuted operation from tab audio indicator, play/resume from
Fennec's media control.
MozReview-Commit-ID: 5mDqDBTnBOr
--HG--
extra : rebase_source : e9d4c3a41ce9a994ef4d44f059537a69f27c7c1e
On Fennec, we would use external app (Android view) to play the media whih is
unsupported by gecko. We implement some special logic in error sink.
(1) dispatch "OpenMediaWithExternalApp" event
we use this event to start the android video player
(2) doesn't dispatch "error" event
some JS players won't let user to trigger play() again after receving the "error".
So we don't dispatch that event if we want to play the unsupported media more than once.
MozReview-Commit-ID: 7fZK5hdvaOG
--HG--
extra : rebase_source : 929db331c22e31a74f76dfa89a99a8adac65d0f6
Error sink would be response for the error handling, we could write different
error dispatching stragedies for different situation. eg. if we can play
unsupported type media with external app, we won't dispatch the "error" event on fennec.
MozReview-Commit-ID: Lm4x9ksspAY
--HG--
extra : rebase_source : 05331714425ea111d21f06fc03abfc1b016654ca
The first checking condition in the IsAllowedPlay() is used to prevent the play() operation
is called by untrusted JS when media.autoplay.enabled=false. Therefore, we don't need to check
that in CanActivateAutoplay().
MozReview-Commit-ID: 6yqoG8ISyra
--HG--
extra : rebase_source : a3e52a1a5591691f503d7d4ca78dda63c05aef27
Because the agent's initialization might fail if we don't get the valid inner window, we need to
check whether the agent exists before calling the agent's method.
MozReview-Commit-ID: IUuvyGh7CMd
--HG--
extra : rebase_source : 54d0811aad736abdbac5ae7c3cd8cfebed88923a
We don't want to stop the loading process even we canceled the play operation.
MozReview-Commit-ID: FyPqBlDKYo0
--HG--
extra : rebase_source : fdbc4390a7763bdbe26e8b809d977234bb5360ea
The old way is to start playing first, and then block the media element. This
way is too complicated because it involves lots of interal state and isn't intuitive.
The new way is to ignore the play if the media element should be blocked. It's
easy to know and we doesn't need to keep any internal states because we don't play
the media element.
MozReview-Commit-ID: B20e0pvXES4
--HG--
extra : rebase_source : 6bff5447783c2997050e5c69884afe2c85ddf382
We create audio channel agent in the beginning in oreder to use some agent's methods.
But the agent is still started after media element starting playing.
MozReview-Commit-ID: KPGb7snB2t7
--HG--
extra : rebase_source : dba4b687f572d520481721f48a0b4e9796f73e1f
We uses "media-playback" event to notify fennec media control about media start
and end. However, if we resume media which was paused by media control, it won't
send any notification to JAVA side so that the MediaControlService can't change
the correct playing icon.
Therefore, we create new event to inform this situation.
MozReview-Commit-ID: zScaHxvHXM
--HG--
extra : rebase_source : e1434840de36d8621a58fc7406b0f42673a2f3db
This means 'waitingforkey' will be fired at a predictable time.
MozReview-Commit-ID: HMt1RbgrbuR
--HG--
extra : rebase_source : cb8c36eacd3e78ae5105cd30da7a51d8241dbd5b
Since I want to use more agent's functions in MediaElement and I don't think these functions need to be exposed on IDL level. (for other languages binding)
Therefore, I want to use AudioChannelAgent directly in MediaElement.
MozReview-Commit-ID: 43FvDeLpZPt
--HG--
extra : rebase_source : 78741d791eb66cfb6223866ce823f217e3438fdb
Enable nsAttrValue::EnumTable to be initialized with enum. So, we could get rid
of the castings in EnumTable. Fix EnumTable initialization comment.
For those untyped enumerations, declare them with uint8_t, as to other typed
enumerations with type size larger than int16_t, force casting to int16_t.
Use {nullptr,0} instead of {0} to represent the last entry.
MozReview-Commit-ID: 7Dma3Apkmxj
--HG--
extra : rebase_source : b2289866c4c33d80c8e170727bf109d018d92f67
This adds support for HTMLMediaElement.mozCaptureStream() and
mozCaptureStreamUntilEnded() for a HTMLMediaElement playing a MediaStream.
This is up to spec, while capturing a HTMLMediaElement playing a file is not.
This incompatibility means we cannot mix sources for the returned MediaStream.
As such, a MediaStream returned while the HTMLMediaElement was playing a file
will only have content while the element is playing files. If the src changes
to a MediaStream, the stream will be empty.
It works the same way if a MediaStream was captured while the HTMLMediaElement
was playing another MediaStream.
This is due to TrackID management - MediaDecoder doesn't care, and creates new
tracks when you seek, so users are unable to keep track, while for MediaStream
we control everything from main thread and keep track of the TrackIDs used
previously.
This also adds a separate path from MediaElementAudioSourceNode so that we don't
forward video tracks when the returned MediaStream is only used internally for
WebAudio. We should in that case not require a DOMMediaStream but just forwarding
tracks to a TrackUnionStream should be enough, and will save us some cpu cycles.
This is however fine for now as it's simpler.
MozReview-Commit-ID: Bg8hESDISDU
--HG--
extra : rebase_source : 83885a73ec8cfc5fbe3c30a9330a52cd6b6dff12
extra : source : f1aec79078869c0a6435a1c06957c649d7a40dd9
This prepares HTMLMediaElement for having a separate MediaStreamTrackSource for
MediaStreams, StreamCaptureTrackSource.
MozReview-Commit-ID: FVrYxFgvXgA
--HG--
extra : rebase_source : 5c162a0e861fa693fea0ba6b94b8e45446c0c13c
extra : source : a9151ac77a81573b8dbd9fee9c8aa09ba8dc7812
Bubble information from SamplesWaitingForKey to an HTMLMediaElement so that we
can emit a waitingForKey event. If we are unable to decode more samples due to
needing a key the event will be signalled. See
http://w3c.github.io/encrypted-media/#dom-evt-waitingforkey for more information
on this event.
The code in place before this patch handles updating readyState when we are
waiting for a key, this patch adds the event which should be emitted in such a
case. The spec defines certain preconditions should be the case before running
the algo to emit this event. For example, the element should potentially be
playing, and it should have at least HAVE_FUTURE_DATA ready state. This is not
strictly true for when the new code is run, due how existing code handles ready
state. We are honoring the spirit of the spec, though the letter of the spec is
lightly gone against in the handling of the preconditions.
MozReview-Commit-ID: LKlDd4wkRSE
--HG--
extra : rebase_source : 2c61fc41636e430afa23240ad5d26c886124d87f
After a video has been playing while hidden for a certain time, count the time
until it is not hidden anymore (or it has finished playing), to test-drive how
much decoding time would have been saved by the video-decode-suspend feature.
Note that this is done inside HTMLMediaElement by simulating what should happen
in the MDSM, because instrumenting the MDSM itself and friends would have been
harder and more intrusive.
MozReview-Commit-ID: LdxhPtmoXeA
--HG--
extra : rebase_source : 151e1f1383ab5c445eb8c957be8363340cdc4ab1
After a video has been playing while hidden for a certain time, count the time
until it is not hidden anymore (or it has finished playing), to test-drive how
much decoding time would have been saved by the video-decode-suspend feature.
Note that this is done inside HTMLMediaElement by simulating what should happen
in the MDSM, because instrumenting the MDSM itself and friends would have been
harder and more intrusive.
MozReview-Commit-ID: LdxhPtmoXeA
--HG--
extra : rebase_source : c4063d7c39b56e62e4f397bc21ef889ed14307c8
If the timer is currently running, add started time segment until now to
Total(), and add 1 to Count().
This ensures correct values are returned without having to Pause().
MozReview-Commit-ID: JSBvL93GtkE
--HG--
extra : rebase_source : 86923c39e54c778151812a55e2ad9e4e010047fd
Note that this is a simple duration counter based on the existing (non-hidden)
play-time, but it only counts when video is playing while hidden.
There is no bucketing yet, future probes may add finer-grained information.
MozReview-Commit-ID: DUfryXjGBAN
--HG--
extra : rebase_source : 4d0bd7f60329dba6c6a6ab039cc733315c50b686
1. If mHasUserInteraction MediaElement is false, don't run the TimeMarchesOn because the element is not played. 2. Update the activeCueList only in TimeMarchesOn(). 3. Run TimeMarchesOn() at the beginning of play. r=rillian
MozReview-Commit-ID: BhwsIfRm3B2
--HG--
extra : rebase_source : 9713d4f467f1d708f65a25e54435d0c6e8ff1816
This function is no longer MSE-specific, so use a more general
ReportTelemetry() name for it.
MozReview-Commit-ID: JU7S4pEFLWk
--HG--
extra : rebase_source : 2a8a9e2e3d07df51c32c98796ebedb6f64c9fef4
Rename the VIDEO_MSE_PLAY_TIME_MS telemetry probe to just
VIDEO_PLAY_TIME_MS and make it active for all video playback.
We were using this to track MSE deployment success. Now we'd
like to do something similar for video playback in general,
regardless of the origin. This allows us to simplify the
collection code somewhat.
MozReview-Commit-ID: 7s8pOQWipf4
DecoderDoctorDiagnostics are now used at places where Firefox Chrome and/or
websites checks whether some media formats may be played:
- audio|video.canPlayType()
- audio|video resource loader
- MediaSource.IsTypeSupported()
- MediaSource.AddSourceBuffer()
MozReview-Commit-ID: B1KdjXODq9j
HTMLMediaElement needs special protection when playing a stream since its
ImageContainer can outlive the video track of a stream.
Consider for instance when a (cross-origin) video track is removed from a
DOMMediaStream by a user and the remaining video track (non-CORS) does not yet
contain any actual video frames. The HTMLMediaElement will display a frame from
the removed track but the DOMMediaStream's principal has been updated to not
include the principal from the removed track.
With this patch we handle this by letting VideoFrameContainer notify
HTMLMediaElement when it has flushed out all video frames belonging to a
certain PrincipalHandle. I.e., when a new PrincipalHandle has been applied to the
underlying ImageContainer.
MozReview-Commit-ID: LvIZPl6Rdgj
--HG--
extra : rebase_source : cfbad5e5e7f43af4da4bfc213494b7b8e22cde17
This makes it consistent with PrincipalChangeObserver.
MozReview-Commit-ID: 91PtqFZRcW6
--HG--
extra : rebase_source : e39abb668be7fbd0dae0a701ec17b048c8761879
The bulk of this commit was generated with a script, executed at the top
level of a typical source code checkout. The only non-machine-generated
part was modifying MFBT's moz.build to reflect the new naming.
CLOSED TREE makes big refactorings like this a piece of cake.
# The main substitution.
find . -name '*.cpp' -o -name '*.cc' -o -name '*.h' -o -name '*.mm' -o -name '*.idl'| \
xargs perl -p -i -e '
s/nsRefPtr\.h/RefPtr\.h/g; # handle includes
s/nsRefPtr ?</RefPtr</g; # handle declarations and variables
'
# Handle a special friend declaration in gfx/layers/AtomicRefCountedWithFinalize.h.
perl -p -i -e 's/::nsRefPtr;/::RefPtr;/' gfx/layers/AtomicRefCountedWithFinalize.h
# Handle nsRefPtr.h itself, a couple places that define constructors
# from nsRefPtr, and code generators specially. We do this here, rather
# than indiscriminantly s/nsRefPtr/RefPtr/, because that would rename
# things like nsRefPtrHashtable.
perl -p -i -e 's/nsRefPtr/RefPtr/g' \
mfbt/nsRefPtr.h \
xpcom/glue/nsCOMPtr.h \
xpcom/base/OwningNonNull.h \
ipc/ipdl/ipdl/lower.py \
ipc/ipdl/ipdl/builtin.py \
dom/bindings/Codegen.py \
python/lldbutils/lldbutils/utils.py
# In our indiscriminate substitution above, we renamed
# nsRefPtrGetterAddRefs, the class behind getter_AddRefs. Fix that up.
find . -name '*.cpp' -o -name '*.h' -o -name '*.idl' | \
xargs perl -p -i -e 's/nsRefPtrGetterAddRefs/RefPtrGetterAddRefs/g'
if [ -d .git ]; then
git mv mfbt/nsRefPtr.h mfbt/RefPtr.h
else
hg mv mfbt/nsRefPtr.h mfbt/RefPtr.h
fi
--HG--
rename : mfbt/nsRefPtr.h => mfbt/RefPtr.h
Other modules than MediaTrackLists may want to receive updates on a
DOMMediaStream's track set. This moves the MediaTrackListListener out of
the MediaTrackList class into DOMMediaStream as a general interface.
The logic for adding MediaTracks to the MediaTrackList when
MediaStreamTracks are added or removed from a DOMMediaStream is moved to
HTMLMediaElement as this fits the model better - HTMLMediaElement is the
owner of the MediaTrackLists.
--HG--
extra : commitid : 3I8mAeBB3oL
extra : rebase_source : 66b8ffcfb5343811c181e4169f295b08494f2ee0
This lets us separate tracks by ownership like so:
* Input - Owned by the producer of the DOMMediaStream (gUM etc.)
* Owned - Contains Input tracks (per above) or tracks cloned tracks
if this DOMMediaStream is a clone.
* Playback - Contains Owned tracks plus tracks addTrack()ed to this
DOMMediaStream minus tracks removeTrack()ed from this
DOMMediaStream.
--HG--
extra : commitid : GPSNwBVyD4j
extra : rebase_source : fba22e96c6c65a74e012509f3da67a4d7df7a244
Other modules than MediaTrackLists may want to receive updates on a
DOMMediaStream's track set. This moves the MediaTrackListListener out of
the MediaTrackList class into DOMMediaStream as a general interface.
The logic for adding MediaTracks to the MediaTrackList when
MediaStreamTracks are added or removed from a DOMMediaStream is moved to
HTMLMediaElement as this fits the model better - HTMLMediaElement is the
owner of the MediaTrackLists.
--HG--
extra : commitid : FxucwRqUZUo
This lets us separate tracks by ownership like so:
* Input - Owned by the producer of the DOMMediaStream (gUM etc.)
* Owned - Contains Input tracks (per above) or tracks cloned tracks
if this DOMMediaStream is a clone.
* Playback - Contains Owned tracks plus tracks addTrack()ed to this
DOMMediaStream minus tracks removeTrack()ed from this
DOMMediaStream.
--HG--
extra : commitid : Kvj9RrN9MgP
When autoplay is disabled, the media element was not detecting user
initiated seeking so when a script attempted to play after seeking,
playing would be blocked.
The bulk of this commit was generated by running:
run-clang-tidy.py \
-checks='-*,llvm-namespace-comment' \
-header-filter=^/.../mozilla-central/.* \
-fix
When navigating away from a document, we mute the playing media elements
through the NotifyOwnerDocumentActivityChanged() notification.
Sometimes, that function may notify the audio channel agent through its
call to AddRemoveSelfReference() which may call
UpdateAudioChannelPlayingState() and notify the agent, but when we're
navigating away from the page, playingThroughTheAudioChannel will always
be equal to mPlayingThroughTheAudioChannel, which causes us to not
notify the audio channel agent.
This patch fixes this by separating NotifyOwnerDocumentActivityChanged()
from its internal consumers, and forcefully notifying the audio channel
agent when we navigate away.
When navigating away from a document, we mute the playing media elements
through the NotifyOwnerDocumentActivityChanged() notification.
Sometimes, that function may notify the audio channel agent through its
call to AddRemoveSelfReference() which may call
UpdateAudioChannelPlayingState() and notify the agent, but when we're
navigating away from the page, playingThroughTheAudioChannel will always
be equal to mPlayingThroughTheAudioChannel, which causes us to not
notify the audio channel agent.
This patch fixes this by separating NotifyOwnerDocumentActivityChanged()
from its internal consumers, and forcefully notifying the audio channel
agent when we navigate away.
When navigating away from a document, we mute the playing media elements
through the NotifyOwnerDocumentActivityChanged() notification.
Sometimes, that function may notify the audio channel agent through its
call to AddRemoveSelfReference() which may call
UpdateAudioChannelPlayingState() and notify the agent, but when we're
navigating away from the page, playingThroughTheAudioChannel will always
be equal to mPlayingThroughTheAudioChannel, which causes us to not
notify the audio channel agent.
This patch fixes this by separating NotifyOwnerDocumentActivityChanged()
from its internal consumers, and forcefully notifying the audio channel
agent when we navigate away.
