Android: Don't hold frame lock during readback

Android: Don't hold frame lock during readback

The problem with this is that it might keep the browser-side
tiles from ever getting freed if for some reason the copy output
request does not finish. And currently there are no such
guarantees for example if the app goes to the background and we don't
have a context and cannot composite.

Also, it would cause jank since the lock keeps from submitting new
frames from the renderer.

As far as readback requests are concerned, this would not cause
the readback to be dropped even if we destroyed the Surface since
it's garbage-collected and there should still be a GC root through
the parent Surface and the hidden layer we attach until the readback
is completed.

Remove more of this logic and public API in a follow-up.

BUG=636628
Review-Url: https://codereview.chromium.org/2241633002
Cr-Commit-Position: refs/heads/master@{#411523}
(cherry picked from commit 9df27b364447148d91e8afe8589ab0914fbb3688)

Committed: https://chromium.googlesource.com/chromium/src/+/ba6da7852ca0d9ef7708f23a8b7c0fd1f93c2cd8

[no sievers, 2016-08-15 18:57:58]

Description was changed from

==========
Android: Don't hold frame lock during readback

The problem with this is that it might keep the browser-side
tiles from ever getting freed if for some reason the copy output
request does not finish. And currently there are no such
guarantees for example if the app goes to the background and we don't
have a context and cannot composite.

Also, it would cause jank since the lock keeps from submitting new
frames from the renderer.

As far as readback requests are concerned, this would not cause
the readback to be dropped even if we destroyed the Surface since
it's garbage-collected and there should still be a GC root through
the parent Surface and the hidden layer we attach until the readback
is completed.

Remove more of this logic and public API in a follow-up.

BUG=636628

Review-Url: https://codereview.chromium.org/2241633002
Cr-Commit-Position: refs/heads/master@{#411523}
(cherry picked from commit 9df27b364447148d91e8afe8589ab0914fbb3688)
==========

to

==========
Android: Don't hold frame lock during readback

The problem with this is that it might keep the browser-side
tiles from ever getting freed if for some reason the copy output
request does not finish. And currently there are no such
guarantees for example if the app goes to the background and we don't
have a context and cannot composite.

Also, it would cause jank since the lock keeps from submitting new
frames from the renderer.

As far as readback requests are concerned, this would not cause
the readback to be dropped even if we destroyed the Surface since
it's garbage-collected and there should still be a GC root through
the parent Surface and the hidden layer we attach until the readback
is completed.

Remove more of this logic and public API in a follow-up.

BUG=636628

Review-Url: https://codereview.chromium.org/2241633002
Cr-Commit-Position: refs/heads/master@{#411523}
(cherry picked from commit 9df27b364447148d91e8afe8589ab0914fbb3688)

Committed:
https://chromium.googlesource.com/chromium/src/+/ba6da7852ca0d9ef7708f23a8b7c...
==========

[no sievers, 2016-08-15 18:57:59]

Committed patchset #1 (id:1) manually as
ba6da7852ca0d9ef7708f23a8b7c0fd1f93c2cd8.