Chromium plumbing for Screen Orientation API orientationchange events. 

This is using RenderViewObserver::OrientationChangeEvent and dispatch 
the information down to the renderer. More will come with locking 
and unlocking abilities. 

BUG=162827

Review URL: https://codereview.chromium.org/176963016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253911 0039d316-1c4b-4281-b951-d872f2087c98
Use SparseArrays instead of HashMaps with Integer keys.

BUG=347356
NOTRY=true

Review URL: https://codereview.chromium.org/182533003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253912 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253912
Android: integrates ThreadWatcher with application life-cycle.

On android, the thread watcher has a potential battery implication by
sending pings to all threads.
When the activity onStop() is called, stop the thread watcher.

BUG=333909
TEST=ThreadWatcherAndroidTest.*

Review URL: https://codereview.chromium.org/154793002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253913 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253913