Estimate GPU latency in OutputSurface

This adds a GpuLatencyEstimate method to OutputSurface. The
estimate is computed based on recent GPU latency, found
using LatencyQueries (GL_LATENCY_QUERY_CHROMIUM). 

BUG=243459

Review URL: https://codereview.chromium.org/17631003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228030 0039d316-1c4b-4281-b951-d872f2087c98
Adds a full QWERTY layout to the Virtual Keyboard.


BUG=297772

Review URL: https://codereview.chromium.org/26258003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228031 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228031
Prevent extension side-enabling.

Review URL: https://codereview.chromium.org/26714003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228032 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228032