Always make context current in ViewManager's BitmapUploader, be laxer in SurfaceResourceHolder

Always make context current in ViewManager's BitmapUploader, be laxer in SurfaceResourceHolder

When in the component build multiple threads (apps) will use the same
view manager client lib and could fight over the current GL context, so
always make our context current in BitmapUploader.

When shutting down abrubtly (i.e. when losing a connection to an app),
the client will not necessarily properly unref all resources it uses.
DCHECKing here isn't helpful, so just skip over resources that are not
fully unreffed.

R=ben@chromium.org

Committed: https://crrev.com/2504061c3b70cd2dc6748bfe4da2b8e020cecb14
Cr-Commit-Position: refs/heads/master@{#294943}

[Ben Goodger (Google), 2014-09-15 22:07:44]

lgtm

[jamesr, 2014-09-15 22:48:02]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-09-15 22:56:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/569173007/1

[commit-bot: I haz the power, 2014-09-16 00:34:41]

Committed patchset #1 (id:1) as ae7ed5cdd21b459c8a07f41087d5b48e3dd5c8f6

[commit-bot: I haz the power, 2014-09-16 00:40:08]

Patchset 1 (id:??) landed as
https://crrev.com/2504061c3b70cd2dc6748bfe4da2b8e020cecb14
Cr-Commit-Position: refs/heads/master@{#294943}