Cherry-pick: [Android WebView] Do not block GetOffscreenContextProviderForMainThread

Clean cherry-pick of

Original description:

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: 13328348

Change-Id: I1ade9f1c1b738fdbd5045fb7523958e5eb2c672d
1 file changed