aw: Move HardwareRenderer out of BrowserViewRenderer

Hardware initialization now is done as part of HardwareRenderer constructor
and destructor. AwContents now directly owns HardwareRenderer and post
results back to BrowserViewRenderer where needed.

Expose View.executeHardwareAction to chromium and use it to run hardware
only code.

Also take this opportunity to clean up unneeded public draw_gl.h and
draw_sw.h interfaces.

Rolled corresponding AOSP change:
https://android-review.googlesource.com/#/c/83824/

BUG=344087
NOTRY=true

Review URL: https://codereview.chromium.org/185133003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254957 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254957