Telemetry: document.documentElement.scrollTop/Left is zero

In order for bug 157855 to get fixed without breaking a related telemetry unit test (page/actions/scroll_unittest.py), this patch changes the way  scrollTop property is checked: it uses an annotation similar to the how real world  WebPages do, where both documentElement and body is checked for cross browser compatibility.

Once bug 157855, it should be encouraged to adopt scrollTop of documentElement only.

BUG=302707

Review URL: https://codereview.chromium.org/25541005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226872 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226872
Revert 225651 "Disabled flaky EndToEndTests/EndToEndTest.LargePo..."

> Disabled flaky EndToEndTests/EndToEndTest.LargePostNoPacketLoss.
> 
> BUG=297040
> R=rch@chromium.org
> 
> Review URL: https://codereview.chromium.org/24804003

TBR=rtenneti@chromium.org

Review URL: https://codereview.chromium.org/25949002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226873 0039d316-1c4b-4281-b951-d872f2087c98
Observe keyboard notifications in docked layout

BUG=303456

Review URL: https://codereview.chromium.org/25740005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226874 0039d316-1c4b-4281-b951-d872f2087c98
Avoid crash when playing corrupt audio

Corrupt audio data in a media file can cause a crash if the number of channels
exceeds the limit that Chrome supports. Fix is to return an error if the number
of channels is too large, so that the buffer allocation is not attempted.

BUG=301985
TEST=Video now plays without crashing (there is no sound from the corrupt audio portion)

Review URL: https://codereview.chromium.org/25772003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226875 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226875