[Android WebView] Do not block GetOffscreenContextProviderForMainThread

Before this, we fail create a main thread shared context if there are no
webviews in hardware initialized mode. The future plan is for
accelerated 2d canvas and webgl to use a shared context with the gpu
thread service, but keep inline video using the ui thread service.

Currently only video uses main thread context for webview, so for now,
only gate context creation for main video on having a
hardware-initalized webview. This makes turning on accelerated canvas
more convenient.

BUG=332146

Review URL: https://codereview.chromium.org/137443020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245613 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245613
Allow the asan_coverage GYP flag to accept arbitrary values.

We're experimenting with using values other than 0 or 1 to control coverage
granularity.

BUG=324216
TBR=glider@chromium.org

Review URL: https://codereview.chromium.org/130503011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245614 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245614