Set up field trial for precache experiment

By default, this trial is disabled.

BUG=309216

Review URL: https://codereview.chromium.org/151183006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250821 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250821
[Android] Lint pylib/host_driven.

BUG=168518

Review URL: https://codereview.chromium.org/159853010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250822 0039d316-1c4b-4281-b951-d872f2087c98
With --site-per-process, avoid a crash when a subframe process goes away.

We need to clear out the children of any nodes that are affected by the
crash, not the entire FrameTree.

BUG=338508
TEST=Killing an iframe process with --site-per-process shows a green rectangle.
R=ajwong@chromium.org, nasko@chromium.org

Review URL: https://codereview.chromium.org/156303004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250823 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250823
Add tdresser to OWNERS of ui/events/gestures.

Review URL: https://codereview.chromium.org/160603002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250824 0039d316-1c4b-4281-b951-d872f2087c98
[Win] Unbreak the new avatar bubble size when using the embedded view.

(the embedded view is wider than the fixed size of the bubble)

BUG=334761

Review URL: https://codereview.chromium.org/137193005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250825 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250825