Cherry pick [Android] Support unfocusable container views.

This solves the S-Pen selection problem for GMail in M37.

Bug: 18066784,18726212

Original change description:

If the ContentViewCore container view is not focusable (which can
happen when it's emebedded in an app via android webview), we
were clearing the RWHVA notion of focus when the RenderView was
swapped out. As the view is never focusable again, chromium never
considers this view focused and as such, text selection did not

We support this type of container view by always treating it focused
from Chromium's point of view.

(internal b/18066784)

Change-Id: If08372c93ff0c87b483f0b408f04247764db2c56
Cr-Commit-Position: refs/heads/master@{#303071}
(cherry picked from commit f66cc3b6f091903a97b577e413da0c2acd80d3b7)
1 file changed