cc: Control defer_commits logic by Scheduler

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index 0f7a2a3dee6baae9dd219c6d3c02f36c4025af2e..246c52afdedfd9e8ef93d4cd65b7ad3264ebe2c8 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -437,13 +437,16 @@ void ThreadProxy::SetDeferCommits(bool defer_commits) {
   else
     TRACE_EVENT_ASYNC_END0("cc", "ThreadProxy::SetDeferCommits", this);
 
-  if (!main().defer_commits && main().pending_deferred_commit) {
-    Proxy::MainThreadTaskRunner()->PostTask(
-        FROM_HERE,
-        base::Bind(&ThreadProxy::BeginMainFrame,
-                   main_thread_weak_ptr_,
-                   base::Passed(&main().pending_deferred_commit)));
-  }
+  Proxy::ImplThreadTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&ThreadProxy::SetDeferCommitsOnImplThread,
+                 impl_thread_weak_ptr_,
+                 defer_commits));
+}
+
+void ThreadProxy::SetDeferCommitsOnImplThread(bool defer_commits) const {
+  DCHECK(IsImplThread());
+  impl().scheduler->SetDeferCommits(defer_commits);
 }
 
 bool ThreadProxy::CommitRequested() const {
@@ -702,14 +705,6 @@ void ThreadProxy::BeginMainFrame(
   TRACE_EVENT_SYNTHETIC_DELAY_BEGIN("cc.BeginMainFrame");
   DCHECK(IsMainThread());
 
-  if (main().defer_commits) {
-    main().pending_deferred_commit = begin_main_frame_state.Pass();
-    layer_tree_host()->DidDeferCommit();
-    TRACE_EVENT_INSTANT0(
-        "cc", "EarlyOut_DeferCommits", TRACE_EVENT_SCOPE_THREAD);
-    return;
-  }
-
   // If the commit finishes, LayerTreeHost will transfer its swap promises to
   // LayerTreeImpl. The destructor of ScopedSwapPromiseChecker aborts the
   // remaining swap promises.
@@ -719,20 +714,22 @@ void ThreadProxy::BeginMainFrame(
   main().commit_request_sent_to_impl_thread = false;
   main().animate_requested = false;
 
-  if (!layer_tree_host()->visible()) {
+  bool need_to_abort_begin_main_frame = true;
+  if (main().defer_commits) {
+    layer_tree_host()->DidDeferCommit();
+    TRACE_EVENT_INSTANT0("cc",
+                         "EarlyOut_DeferCommits",
+                         TRACE_EVENT_SCOPE_THREAD);

[brianderson, 2014/11/19 19:55:07]

If we abort a commit because we are deferring commits, we should probably call
SetNeedsCommit to make sure we eventually get another BeginMainFrame. Otherwise
we are assuming blink will SetNeedsCommit when it stops deferring commits, which
I don't think is a safe assumption to make. Even if it is a true assumption
today, it may not be in the future.

Same for the SingleThreadProxy.

[simonhong, 2014/11/26 15:52:53]

SetNeedsCommit() is added when SetDeferCommits(false) is called (when changed
from true to false).

+  } else if (!layer_tree_host()->visible()) {
     TRACE_EVENT_INSTANT0("cc", "EarlyOut_NotVisible", TRACE_EVENT_SCOPE_THREAD);
-    bool did_handle = false;
-    Proxy::ImplThreadTaskRunner()->PostTask(
-        FROM_HERE,
-        base::Bind(&ThreadProxy::BeginMainFrameAbortedOnImplThread,
-                   impl_thread_weak_ptr_,
-                   did_handle));
-    return;
-  }
-
-  if (layer_tree_host()->output_surface_lost()) {
+  } else if (layer_tree_host()->output_surface_lost()) {
     TRACE_EVENT_INSTANT0(
         "cc", "EarlyOut_OutputSurfaceLost", TRACE_EVENT_SCOPE_THREAD);
+  } else {
+    need_to_abort_begin_main_frame = false;
+  }
+
+  if (need_to_abort_begin_main_frame) {
     bool did_handle = false;
     Proxy::ImplThreadTaskRunner()->PostTask(
         FROM_HERE,