cc: Start commit early and block on tree activation

cc: Start commit early and block on tree activation

For discussion not review yet.

This patch allows us to record the next commit while we
are rasterizing the previous commit.

BUG=none yet

[brianderson, 2013-08-10 02:19:15]

This sometimes starts commits way too early, blocking the main thread longer
than necessary, but can help websites with larger commit and raster times.

[Sami, 2013-08-13 15:56:02]

I like the idea for increased parallelism. I wonder if we should make it
tweakable for low end devices or perhaps avoid doing this in prefer smoothness
mode.

https://codereview.chromium.org/22320019/diff/1/cc/trees/thread_proxy.cc
File cc/trees/thread_proxy.cc (right):

https://codereview.chromium.org/22320019/diff/1/cc/trees/thread_proxy.cc#newc...
cc/trees/thread_proxy.cc:890: // We defer forced commits while there is a
pending tree here.
Could this be done in the state machine instead? Seems like it has all the
necessary bits of information already.

[brianderson, 2013-09-07 01:18:54]

Replacing this patch with: https://codereview.chromium.org/23907006.

https://codereview.chromium.org/22320019/diff/1/cc/trees/thread_proxy.cc
File cc/trees/thread_proxy.cc (right):

https://codereview.chromium.org/22320019/diff/1/cc/trees/thread_proxy.cc#newc...
cc/trees/thread_proxy.cc:890: // We defer forced commits while there is a
pending tree here.
On 2013/08/13 15:56:02, Sami wrote:
> Could this be done in the state machine instead? Seems like it has all the
> necessary bits of information already.

Hmm, I'll give that a try. I did it this way because I knew for sure that we
haven't affected state on the impl-thread at this point yet. Doing it in the
scheduler would allow us to defer the commit even later into the process.