Reland of cc: Remove frame queuing from the scheduler.

cc/surfaces/display.cc

Index: cc/surfaces/display.cc
diff --git a/cc/surfaces/display.cc b/cc/surfaces/display.cc
index 670ad22a70a54ab4de967666805e450b9cfbd168..00d88e09e214fcca5a40f03f74dc2c052835b9e0 100644
--- a/cc/surfaces/display.cc
+++ b/cc/surfaces/display.cc
@@ -248,7 +248,7 @@ bool Display::DrawAndSwap() {
   // Run callbacks early to allow pipelining.
   for (const auto& id_entry : aggregator_->previous_contained_surfaces()) {
     Surface* surface = surface_manager_->GetSurfaceForId(id_entry.first);
-    if (surface)
+    if (surface && surface->surface_id() != current_surface_id_)
       surface->RunDrawCallbacks();
   }
 
@@ -325,10 +325,11 @@ bool Display::DrawAndSwap() {
   if (should_swap) {
     swapped_since_resize_ = true;
     for (auto& latency : frame.metadata.latency_info) {
-      TRACE_EVENT_WITH_FLOW1("input,benchmark", "LatencyInfo.Flow",
+      TRACE_EVENT_WITH_FLOW1(
+          "input,benchmark", "LatencyInfo.Flow",
           TRACE_ID_DONT_MANGLE(latency.trace_id()),
-          TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT,
-          "step", "Display::DrawAndSwap");
+          TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT, "step",
+          "Display::DrawAndSwap");
     }
     benchmark_instrumentation::IssueDisplayRenderingStatsEvent();
     renderer_->SwapBuffers(std::move(frame.metadata));
@@ -347,6 +348,12 @@ bool Display::DrawAndSwap() {
     }
   }
 
+  // Run draw callback for root surface after drawing.

[enne (OOO), 2016/09/19 22:11:50]

Can you make this comment more of a 'why' and less of a 'what' so that future
engineers can understand why we break up the callbacks?

[sunnyps, 2016/09/19 23:59:04]

Added comment where we run the callbacks for other surfaces above.

+  Surface* root_surface =
+      surface_manager_->GetSurfaceForId(current_surface_id_);
+  if (root_surface)
+    root_surface->RunDrawCallbacks();
+
   client_->DisplayDidDrawAndSwap();
   return true;
 }