Issue 642738  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e6a3fc3ecf930563d9ad972691e7c8f24c27654f

commit e6a3fc3ecf930563d9ad972691e7c8f24c27654f
Author: dtseng <dtseng@chromium.org>
Date: Wed Dec 14 15:58:02 2016

Expose media controls to accessibility

This cl wires up media controls given a web contents -> AX tree mapping.

Actions:
startDuckingMedia: requests the associated MediaSession start ducking. This gets passed back to the MediaSessionController which eventually relays the new volume multiplier.
stopDuckingMedia: same as above with volume multiplier set to 1.0.
resumeMedia: resumes suspended media
suspendMedia: suspends currently playing media

Events:
mediaStartedPlaying
mediaStoppedPlaying

Note: to see this work, use flag --enable-default-media-session

This would allow a client extension to:
- duck audio on a specific web contents
- observe when a media session is started/stopped

For ChromeVox, we can then allow audio not coming from the TTS extension or the ChromeVox extension (e.g. earcons) to be ducked. This also allows us to duck web contents in the background, longer running media sessions, foreground web contents based on a key command, after a tts start event, etc.

TEST=observe events; play media, stop media; verify media started/stopped come through. Explicitly call start/stop ducking; verify audio ducks/unducks. Also, call resume/suspend and verify audio resumes/suspends.
BUG= 621697 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2550593003
Cr-Commit-Position: refs/heads/master@{#438525}

[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chrome/browser/extensions/api/automation_internal/automation_internal_api.cc
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chrome/browser/resources/chromeos/chromevox/BUILD.gn
[add] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chrome/browser/resources/chromeos/chromevox/cvox2/background/media_automation_handler.js
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chrome/common/extensions/api/automation.idl
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chrome/common/extensions/api/automation_internal.idl
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chrome/renderer/resources/extensions/automation/automation_node.js
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chrome/renderer/resources/extensions/automation_custom_bindings.js
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/chromecast/browser/cast_media_blocker_unittest.cc
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/content/browser/media/session/media_session_impl.h
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/content/public/browser/media_session.h
[modify] https://crrev.com/e6a3fc3ecf930563d9ad972691e7c8f24c27654f/ui/accessibility/ax_enums.idl

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab

commit c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab
Author: dtseng <dtseng@chromium.org>
Date: Thu Dec 29 05:53:19 2016

Support audio ducking and suspension in ChromeVox

- adds options to automatically duck/unduck, suspend/resume audio based on tts events.

BUG= 621697 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2563013003
Cr-Commit-Position: refs/heads/master@{#440940}

[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/extensions/api/automation_internal/automation_internal_api.cc
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/chromevox/background/options.html
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/chromevox/background/options.js
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/chromevox/background/prefs.js
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/common/chrome_extension_externs.js
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/cvox2/background/media_automation_handler.js
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/host/chrome/tts_background.js
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/host/interface/tts_interface.js
[modify] https://crrev.com/c4e9b8f0ec120f1d48ee43cd0e8689439f7388ab/chrome/browser/resources/chromeos/chromevox/strings/chromevox_strings.grd

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d50debe3d51323319ba9b42e2a7d1fde593f3b06

commit d50debe3d51323319ba9b42e2a7d1fde593f3b06
Author: dtseng <dtseng@chromium.org>
Date: Thu Dec 29 06:23:37 2016

Enable default media session when ChromeVox is toggled.

BUG= 621697 

Review-Url: https://codereview.chromium.org/2577713002
Cr-Commit-Position: refs/heads/master@{#440942}

[modify] https://crrev.com/d50debe3d51323319ba9b42e2a7d1fde593f3b06/chrome/browser/chromeos/accessibility/accessibility_manager.cc