cc: Add readback and forced draw states to the Scheduler

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index e383894a7836f9164ceb6cb14e647ce929837622..ecb47a182ceb7b4f757b6b6860b75a7d00a3b515 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -54,9 +54,9 @@ void Scheduler::SetNeedsCommit() {
   ProcessScheduledActions();
 }
 
-void Scheduler::SetNeedsForcedCommit() {
+void Scheduler::SetNeedsForcedCommitForReadback() {
   state_machine_.SetNeedsCommit();
-  state_machine_.SetNeedsForcedCommit();
+  state_machine_.SetNeedsForcedCommitForReadback();
   ProcessScheduledActions();
 }
 
@@ -70,11 +70,6 @@ void Scheduler::DidSwapUseIncompleteTile() {
   ProcessScheduledActions();
 }
 
-void Scheduler::SetNeedsForcedRedraw() {
-  state_machine_.SetNeedsForcedRedraw();
-  ProcessScheduledActions();
-}
-
 void Scheduler::SetMainThreadNeedsLayerTextures() {
   state_machine_.SetMainThreadNeedsLayerTextures();
   ProcessScheduledActions();
@@ -178,7 +173,7 @@ void Scheduler::BeginFrame(const BeginFrameArgs& args) {
 }
 
 void Scheduler::DrawAndSwapIfPossible() {
-  ScheduledActionDrawAndSwapResult result =
+  DrawSwapReadbackResult result =
       client_->ScheduledActionDrawAndSwapIfPossible();
   state_machine_.DidDrawIfPossibleCompleted(result.did_draw);
   if (result.did_swap)
@@ -186,8 +181,7 @@ void Scheduler::DrawAndSwapIfPossible() {
 }
 
 void Scheduler::DrawAndSwapForced() {
-  ScheduledActionDrawAndSwapResult result =
-      client_->ScheduledActionDrawAndSwapForced();
+  DrawSwapReadbackResult result = client_->ScheduledActionDrawAndSwapForced();
   if (result.did_swap)
     has_pending_begin_frame_ = false;
 }
@@ -202,6 +196,7 @@ void Scheduler::ProcessScheduledActions() {
 
   SchedulerStateMachine::Action action;
   do {
+    state_machine_.CheckInvariants();
     action = state_machine_.NextAction();
     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
                  "SchedulerStateMachine",
@@ -223,16 +218,19 @@ void Scheduler::ProcessScheduledActions() {
       case SchedulerStateMachine::ACTION_ACTIVATE_PENDING_TREE:
         client_->ScheduledActionActivatePendingTree();
         break;
-      case SchedulerStateMachine::ACTION_DRAW_IF_POSSIBLE:
+      case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
         DrawAndSwapIfPossible();
         break;
-      case SchedulerStateMachine::ACTION_DRAW_FORCED:
+      case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_FORCED:
         DrawAndSwapForced();
         break;
       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_ABORT:
         // No action is actually performed, but this allows the state machine to
         // advance out of its waiting to draw state without actually drawing.
         break;
+      case SchedulerStateMachine::ACTION_DRAW_AND_READBACK:
+        client_->ScheduledActionDrawAndReadback();

[danakj, 2013/08/30 15:56:41]

How about a DrawAndReadback() method above that can DCHECK the result values are
as expected?

[brianderson, 2013/09/03 22:41:12]

I avoided checking for success because I read somewhere in the code that the
readback could fail in some cases and that would be ok. Is readback always
expected to succeed? Or did you just want to check that did_readback is true if
the draw succeeded?

+        break;
       case SchedulerStateMachine::ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
         client_->ScheduledActionBeginOutputSurfaceCreation();
         break;