[SyncFS] Update histogram.xml for syncfs

Add metrics to SyncFileSystem API usage and configuration of conflict resolution policy.
Corresponding to http://crrev.com/255678

BUG=347424

Review URL: https://codereview.chromium.org/190223002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256481 0039d316-1c4b-4281-b951-d872f2087c98
Stretch CENTER_CROPPED wallpaper to fill screen

If a screen is larger than wallpaper, we used to pain black rectangle on
both side that is not covered by wallpaper. As large monitor becomes more
popular, we decide to scale and crop wallpaper in that case.


BUG=chrome-os-parter:26288

Review URL: https://codereview.chromium.org/189623005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256482 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256481
Mac AVFoundation/QTKit: delay DeviceMonitorMac startup to first GetUserMedia.

Currently DeviceMonitorMac is constructed from BrowserMainLoop in the
first compasses of Chrome bringup. DeviceMonitorMac creates either a
QTKitMonitorImpl or a AVFoundationMonitorImpl, that immediately
starts observing the system capture devices. This monitoring is
not needed until the user actively starts operating the devices,
that happens in MediaStreamManager.

This CL adds a method StartMonitoring() to DeviceMonitorMac that is
exercised from MediaStreamManager::StartMonitoring().

The performance regression in bugs 349616 and 348020 affects only
AVFoundation, but both implementations would benefit from a delayed
startup.

Tested locally via using --[enable/disable]-avfoundation, connecting
and disconnecting devices etc.

BUG=288562, 349616, 348020

Review URL: https://codereview.chromium.org/189443010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256483 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256483