Revert "Enable virtual contexts for all ARM T-6xx models instead of just T-604"

This reverts commit r224977.  Virtual contexts are suspected to cause
black flashes on the Galaxy Note 3.

Note: Turning off virtual contexts will cause serious graphics
corruption on the Galaxy Note 3, Chromium/Chrome Dev/Chrome Beta builds,
but it appears the Galaxy Note 3 has a driver workaround specific to
Chrome Stable.  There is no way to properly test the outcome of this
change without a signed stable build so I intend to submit this
speculatively, then try out a ChromeStable.apk to see if it helped.

NOTRY=true
BUG=306690

Review URL: https://codereview.chromium.org/54543012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232773 0039d316-1c4b-4281-b951-d872f2087c98
Android: fix concurrency issue in DataFetcherImplAndroid.

Methods in DataFetcherImplAndroid are called by different threads.
Shared memory buffer should be protected by a lock in order to
guarantee proper operation of the fetcher.

Without the lock methods like StopFetchingDeviceMotionData()
could modify the shared memory buffer concurrently with a
callback method like GotAcceleration().

BUG=313457
TBR=mvanouwerkerk@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/55143008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232774 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232773
SVN changes up to revision 232774