Change renderer compositor command buffer to be 64kB

Change renderer compositor command buffer to be 64kB

With delegated rendering and either software rasterization or GPU rasterization in a worker context, the compositor context will execute very few commands. Therefore, we can reduce the size of the command buffer from 1MB to 64kB with no effect on performance.

Committed: https://crrev.com/5e420d38f61d4c476a8916a2ff981a5e0330e68b
Cr-Commit-Position: refs/heads/master@{#341874}

[jbauman, 2015-08-03 21:23:44]

jbauman@chromium.org changed reviewers:
+ sievers@chromium.org

[jbauman, 2015-08-03 21:23:45]

This should help reduce memory usage on android. We can probably also do this
with start_transfer_buffer_size, though I'd want to do that in a separate patch.

[no sievers, 2015-08-03 21:42:09]

That's a good idea, but is 16kb maybe a bit aggressive?

In compositor_impl_android.cc we set 64kb for the browser compositor (though
it's of course a bit different, and probably not based on very deep
investigations there).
I think when I looked a long time ago (it was with delegated rendering though),
I was a bit surprised to see us actually using more space in the cmd buffer than
I thought per frame (and then you want to allow for pages with multiple layers,
small tiles, an extra frame pending, prepainting etc.).

[jbauman, 2015-08-04 01:46:47]

On 2015/08/03 21:42:09, sievers wrote:
> That's a good idea, but is 16kb maybe a bit aggressive?
> 
> In compositor_impl_android.cc we set 64kb for the browser compositor (though
> it's of course a bit different, and probably not based on very deep
> investigations there).
> I think when I looked a long time ago (it was with delegated rendering
though),
> I was a bit surprised to see us actually using more space in the cmd buffer
than
> I thought per frame (and then you want to allow for pages with multiple
layers,
> small tiles, an extra frame pending, prepainting etc.).

Ok, switched it to be 64kb instead. Though I'd expect this to need less
command-buffer space than the browser compositor because it has no gl renderer.

[no sievers, 2015-08-04 17:49:10]

lgtm

[jbauman, 2015-08-05 08:16:00]

The CQ bit was checked by jbauman@chromium.org

[commit-bot: I haz the power, 2015-08-05 08:16:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1263213004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1263213004/20001

[commit-bot: I haz the power, 2015-08-05 09:33:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-05 09:34:00]

Patchset 2 (id:??) landed as
https://crrev.com/5e420d38f61d4c476a8916a2ff981a5e0330e68b
Cr-Commit-Position: refs/heads/master@{#341874}