cc: Start commit early and block on tree activation

cc/scheduler/scheduler_state_machine.cc

Index: cc/scheduler/scheduler_state_machine.cc
diff --git a/cc/scheduler/scheduler_state_machine.cc b/cc/scheduler/scheduler_state_machine.cc
index dbc026ca9f2e6be8403ec95fc7509ed13adcd6d6..df0ad9b0134d1801854a84f4c26247d5fad1c32c 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -223,6 +223,7 @@ bool SchedulerStateMachine::ShouldDraw() const {
     return !active_tree_has_been_drawn_ &&
            (commit_state_ == COMMIT_STATE_WAITING_FOR_FIRST_DRAW ||
             commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION ||
+            commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS ||
             (output_surface_state_ != OUTPUT_SURFACE_ACTIVE &&
              !active_tree_is_null_));
   }
@@ -306,12 +307,13 @@ bool SchedulerStateMachine::ShouldSendBeginFrameToMainThread() const {
     return false;
 
   // Only send BeginFrame to the main thread when idle.
-  if (commit_state_ != COMMIT_STATE_IDLE)
+  if (commit_state_ != COMMIT_STATE_IDLE &&
+      commit_state_ != COMMIT_STATE_WAITING_FOR_ACTIVATION)
     return false;
 
   // We can't accept a commit if we have a pending tree.
-  if (has_pending_tree_)
-    return false;
+  //if (has_pending_tree_)
+  //  return false;
 
   // We want to handle readback commits ASAP.
   if (readback_state_ == READBACK_STATE_FORCED_COMMIT_REQUESTED)
@@ -381,6 +383,7 @@ SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
       return ACTION_NONE;
 
     case COMMIT_STATE_FRAME_IN_PROGRESS:
+    case COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS:
       if (ShouldUpdateVisibleTiles())
         return ACTION_UPDATE_VISIBLE_TILES;
       if (ShouldActivatePendingTree())
@@ -398,6 +401,8 @@ SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
       return ACTION_COMMIT;
 
     case COMMIT_STATE_WAITING_FOR_ACTIVATION: {
+      if (ShouldSendBeginFrameToMainThread())
+        return ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD;
       if (ShouldUpdateVisibleTiles())
         return ACTION_UPDATE_VISIBLE_TILES;
       if (ShouldActivatePendingTree())
@@ -452,12 +457,15 @@ void SchedulerStateMachine::UpdateState(Action action) {
       return;
 
     case ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD:
-      DCHECK(!has_pending_tree_);
+      //DCHECK(!has_pending_tree_);
       DCHECK(visible_ ||
              readback_state_ == READBACK_STATE_FORCED_COMMIT_REQUESTED ||
              forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT ||
              output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT);
-      commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
+      if (commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION)
+        commit_state_ = COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS;
+      else
+        commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
       needs_commit_ = false;
       if (readback_state_ == READBACK_STATE_FORCED_COMMIT_REQUESTED)
         readback_state_ = READBACK_STATE_FORCED_COMMIT_PENDING;
@@ -632,7 +640,8 @@ void SchedulerStateMachine::SetNeedsCommit() { needs_commit_ = true; }
 void SchedulerStateMachine::SetNeedsForcedCommitForReadback() {
   DCHECK(readback_state_ == READBACK_STATE_IDLE ||
          readback_state_ == READBACK_STATE_REPLACEMENT_COMMIT_PENDING);
-  if (commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS)
+  if (commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS ||
+      commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS)
     readback_state_ = READBACK_STATE_FORCED_COMMIT_PENDING;
   else
     readback_state_ = READBACK_STATE_FORCED_COMMIT_REQUESTED;
@@ -640,13 +649,15 @@ void SchedulerStateMachine::SetNeedsForcedCommitForReadback() {
 
 void SchedulerStateMachine::FinishCommit() {
   DCHECK(commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS ||
+         commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS ||
          readback_state_ == READBACK_STATE_FORCED_COMMIT_PENDING)
       << ToString();
   commit_state_ = COMMIT_STATE_READY_TO_COMMIT;
 }
 
 void SchedulerStateMachine::BeginFrameAbortedByMainThread(bool did_handle) {
-  DCHECK_EQ(commit_state_, COMMIT_STATE_FRAME_IN_PROGRESS);
+  DCHECK(commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS ||
+         commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS);
   if (readback_state_ == READBACK_STATE_FORCED_COMMIT_REQUESTED) {
     readback_state_ = READBACK_STATE_IDLE;
   } else if (did_handle) {
@@ -688,7 +699,8 @@ void SchedulerStateMachine::SetHasTrees(bool has_pending_tree,
     if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION)
       output_surface_state_ = OUTPUT_SURFACE_ACTIVE;
 
-    DCHECK_EQ(COMMIT_STATE_WAITING_FOR_ACTIVATION, commit_state_);
+    DCHECK(commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION ||
+           commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS);
     if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION) {
       commit_state_ = COMMIT_STATE_WAITING_FOR_FIRST_DRAW;
       forced_redraw_state_ = FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
@@ -696,7 +708,10 @@ void SchedulerStateMachine::SetHasTrees(bool has_pending_tree,
       commit_state_ = COMMIT_STATE_WAITING_FOR_FIRST_DRAW;
       readback_state_ = READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK;
     } else {
-      commit_state_ = COMMIT_STATE_IDLE;
+      if (commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION_AND_FRAME_IN_PROGRESS)
+        commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
+      else
+        commit_state_ = COMMIT_STATE_IDLE;
       if (readback_state_ == READBACK_STATE_REPLACEMENT_COMMIT_ACTIVATING)
         readback_state_ = READBACK_STATE_IDLE;
     }