Allow cc::STP::SetNeedsAnimate to request another commit from a commit

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index b9f6a4849131dfa14431b6f7a0b48dd4fe81fab9..8d543d28a18e6c3239ba0d448f62e49034bf9cf6 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -178,7 +178,8 @@ void SingleThreadProxy::SetNeedsAnimate() {
   TRACE_EVENT0("cc", "SingleThreadProxy::SetNeedsAnimate");
   DCHECK(Proxy::IsMainThread());
   client_->ScheduleAnimation();
-  SetNeedsCommit();
+  DebugScopedSetImplThread impl(this);
+  SetNeedsCommitOnImplThread();

[danakj, 2015/04/28 20:00:44]

This would ScheduleComposite twice, and we should early out of SNA() if SNA()
was already called.

 }
 
 void SingleThreadProxy::SetNeedsUpdateLayers() {
@@ -336,8 +337,7 @@ void SingleThreadProxy::SetNeedsCommit() {
   if (commit_requested_)
     return;
   DebugScopedSetImplThread impl(this);
-  if (scheduler_on_impl_thread_)
-    scheduler_on_impl_thread_->SetNeedsCommit();
+  SetNeedsCommitOnImplThread();
   commit_requested_ = true;
 }