Remove unnecessary setNeedsCompositingUpdate(CompositingUpdateRebuildTree)

Remove unnecessary setNeedsCompositingUpdate(CompositingUpdateRebuildTree)

The RenderLayerCompositor can determine whether it needs to rebuild the tree.
We don't need to dirty this much state.

R=esprehn@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180008

[esprehn, 2014-08-11 22:59:55]

Does adding a new RenderLayer still always cause a rebuild tree later in the
pipeline?

[esprehn, 2014-08-11 23:10:52]

lgtm

[abarth-chromium, 2014-08-11 23:12:25]

The CQ bit was checked by abarth@chromium.org

[abarth-chromium, 2014-08-11 23:13:03]

On 2014/08/11 at 22:59:55, esprehn wrote:
> Does adding a new RenderLayer still always cause a rebuild tree later in the
pipeline?

Nope.  If the RenderLayer is drawn into another composited layer, there's no
need to rebuild the tree.

[commit-bot: I haz the power, 2014-08-11 23:13:23]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/abarth@chromium.org/450403003/1

[abarth-chromium, 2014-08-11 23:31:27]

Committed patchset #1 manually as 180008 (presubmit successful).