cc: Unify use of DidSwapBuffers() and did_request_swap

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index df7f166fd11e831edf504855773a38670e6f6b0d..bc34d4676bfdf0c8396097342006bb0d4f314b03 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -186,6 +186,10 @@ void Scheduler::SetMaxSwapsPending(int max) {
 
 void Scheduler::DidSwapBuffers() {
   state_machine_.DidSwapBuffers();
+
+  // Swap should not occur by readback operation.

[Sami, 2014/05/01 10:21:44]

s/by/inside/?

[simonhong, 2014/05/08 01:14:57]

Done.

+  DCHECK(!IsInsideAction(SchedulerStateMachine::ACTION_DRAW_AND_READBACK));
+
   // There is no need to call ProcessScheduledActions here because
   // swapping should not trigger any new actions.
   if (!inside_process_scheduled_actions_) {
@@ -594,9 +598,8 @@ bool Scheduler::IsBeginMainFrameSent() const {
 }
 
 void Scheduler::DrawAndSwapIfPossible() {
-  DrawSwapReadbackResult result =
-      client_->ScheduledActionDrawAndSwapIfPossible();
-  state_machine_.DidDrawIfPossibleCompleted(result.draw_result);
+  DrawResult result = client_->ScheduledActionDrawAndSwapIfPossible();
+  state_machine_.DidDrawIfPossibleCompleted(result);
 }
 
 void Scheduler::DrawAndSwapForced() {

[Sami, 2014/05/01 10:21:44]

Looks like this and the next function could be removed in favor of just calling
the client directly.

[simonhong, 2014/05/08 01:14:57]

Yep. Both are removed.

@@ -604,8 +607,7 @@ void Scheduler::DrawAndSwapForced() {
 }
 
 void Scheduler::DrawAndReadback() {
-  DrawSwapReadbackResult result = client_->ScheduledActionDrawAndReadback();
-  DCHECK(!result.did_request_swap);
+  client_->ScheduledActionDrawAndReadback();
 }
 
 void Scheduler::ProcessScheduledActions() {