cc: Implement deadine scheduling disabled by default

cc/scheduler/scheduler_state_machine.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/scheduler/scheduler_state_machine.h"
 
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "base/values.h"
 
 namespace cc {
 
 SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
     : settings_(settings),
       output_surface_state_(OUTPUT_SURFACE_LOST),
+      begin_frame_state_(BEGIN_FRAME_STATE_IDLE),
       commit_state_(COMMIT_STATE_IDLE),
       texture_state_(LAYER_TEXTURE_STATE_UNLOCKED),
       forced_redraw_state_(FORCED_REDRAW_STATE_IDLE),
       readback_state_(READBACK_STATE_IDLE),
       commit_count_(0),
-      current_frame_number_(0),
-      last_frame_number_where_begin_frame_sent_to_main_thread_(-1),
-      last_frame_number_swap_performed_(-1),
-      last_frame_number_where_update_visible_tiles_was_called_(-1),
+      begin_frame_count_(0),
+      last_begin_frame_count_swap_performed_(-1),
+      last_begin_frame_count_begin_frame_sent_to_main_thread_(-1),
+      last_begin_frame_count_update_visible_tiles_was_called_(-1),
       consecutive_failed_draws_(0),
       needs_redraw_(false),
       swap_used_incomplete_tile_(false),
       needs_commit_(false),
       main_thread_needs_layer_textures_(false),
-      inside_begin_frame_(false),
       visible_(false),
       can_start_(false),
       can_draw_(false),
       has_pending_tree_(false),
       pending_tree_is_ready_for_activation_(false),
       active_tree_needs_first_draw_(false),
       draw_if_possible_failed_(false),
       did_create_and_initialize_first_output_surface_(false) {}
 
 const char* SchedulerStateMachine::OutputSurfaceStateToString(
     OutputSurfaceState state) {
   switch (state) {
     case OUTPUT_SURFACE_ACTIVE:
       return "OUTPUT_SURFACE_ACTIVE";
     case OUTPUT_SURFACE_LOST:
       return "OUTPUT_SURFACE_LOST";
     case OUTPUT_SURFACE_CREATING:
       return "OUTPUT_SURFACE_CREATING";
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
       return "OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT";
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
       return "OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION";
   }
   NOTREACHED();
   return "???";
 }
 
+const char* SchedulerStateMachine::BeginFrameStateToString(
+    BeginFrameState state) {
+  switch (state) {
+    case BEGIN_FRAME_STATE_IDLE:
+      return "BEGIN_FRAME_STATE_IDLE";
+    case BEGIN_FRAME_STATE_INSIDE_BEGIN_FRAME:
+      return "BEGIN_FRAME_STATE_INSIDE_BEGIN_FRAME";
+    case BEGIN_FRAME_STATE_DEADLINE_PENDING:
+      return "BEGIN_FRAME_STATE_DEADLINE_PENDING";
+    case BEGIN_FRAME_STATE_INSIDE_DEADLINE:
+      return "BEGIN_FRAME_STATE_INSIDE_DEADLINE";
+  }
+  NOTREACHED();
+  return "???";
+}
+
 const char* SchedulerStateMachine::CommitStateToString(CommitState state) {
   switch (state) {
     case COMMIT_STATE_IDLE:
       return "COMMIT_STATE_IDLE";
     case COMMIT_STATE_FRAME_IN_PROGRESS:
       return "COMMIT_STATE_FRAME_IN_PROGRESS";
     case COMMIT_STATE_READY_TO_COMMIT:
       return "COMMIT_STATE_READY_TO_COMMIT";
     case COMMIT_STATE_WAITING_FOR_FIRST_DRAW:
       return "COMMIT_STATE_WAITING_FOR_FIRST_DRAW";
@@ skipping 80 matching lines @@
   }
   NOTREACHED();
   return "???";
 }
 
 scoped_ptr<base::Value> SchedulerStateMachine::AsValue() const  {
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue);
 
   scoped_ptr<base::DictionaryValue> major_state(new base::DictionaryValue);
   major_state->SetString("next_action", ActionToString(NextAction()));
+  major_state->SetString("begin_frame_state",
+                         BeginFrameStateToString(begin_frame_state_));
   major_state->SetString("commit_state", CommitStateToString(commit_state_));
   major_state->SetString("texture_state_",
                          TextureStateToString(texture_state_));
   major_state->SetString("output_surface_state_",
                          OutputSurfaceStateToString(output_surface_state_));
   major_state->SetString(
       "forced_redraw_state",
       ForcedRedrawOnTimeoutStateToString(forced_redraw_state_));
   major_state->SetString("readback_state",
                          SynchronousReadbackStateToString(readback_state_));
@@ skipping 21 matching lines @@
       (last_begin_frame_args_.frame_time - base::TimeTicks()).InMicroseconds() /
           1000.0L);
   timestamps_state->SetDouble(
       "6_deadline",
       (last_begin_frame_args_.deadline - base::TimeTicks()).InMicroseconds() /
           1000.0L);
   state->Set("major_timestamps_in_ms", timestamps_state.release());
 
   scoped_ptr<base::DictionaryValue> minor_state(new base::DictionaryValue);
   minor_state->SetInteger("commit_count", commit_count_);
-  minor_state->SetInteger("current_frame_number", current_frame_number_);
+  minor_state->SetInteger("begin_frame_count_", begin_frame_count_);
+
+  minor_state->SetInteger("last_begin_frame_count_swap_performed_",
+                          last_begin_frame_count_swap_performed_);
   minor_state->SetInteger(
-      "last_frame_number_where_begin_frame_sent_to_main_thread",
-      last_frame_number_where_begin_frame_sent_to_main_thread_);
-  minor_state->SetInteger("last_frame_number_swap_performed_",
-                          last_frame_number_swap_performed_);
+      "last_begin_frame_count_begin_frame_sent_to_main_thread_",
+      last_begin_frame_count_begin_frame_sent_to_main_thread_);
   minor_state->SetInteger(
-      "last_frame_number_where_update_visible_tiles_was_called",
-      last_frame_number_where_update_visible_tiles_was_called_);
-  minor_state->SetInteger("consecutive_failed_draws",
+      "last_begin_frame_count_update_visible_tiles_was_called_",
+      last_begin_frame_count_update_visible_tiles_was_called_);
+
+  minor_state->SetInteger("consecutive_failed_draws_",
                           consecutive_failed_draws_);
   minor_state->SetBoolean("needs_redraw", needs_redraw_);
   minor_state->SetBoolean("swap_used_incomplete_tile",
                           swap_used_incomplete_tile_);
   minor_state->SetBoolean("needs_commit", needs_commit_);
   minor_state->SetBoolean("main_thread_needs_layer_textures",
                           main_thread_needs_layer_textures_);
-  minor_state->SetBoolean("inside_begin_frame", inside_begin_frame_);
   minor_state->SetBoolean("visible", visible_);
   minor_state->SetBoolean("can_start", can_start_);
   minor_state->SetBoolean("can_draw", can_draw_);
   minor_state->SetBoolean("has_pending_tree", has_pending_tree_);
   minor_state->SetBoolean("pending_tree_is_ready_for_activation_",
                           pending_tree_is_ready_for_activation_);
   minor_state->SetBoolean("active_tree_needs_first_draw_",
                           active_tree_needs_first_draw_);
   minor_state->SetBoolean("draw_if_possible_failed", draw_if_possible_failed_);
   minor_state->SetBoolean("did_create_and_initialize_first_output_surface",
                           did_create_and_initialize_first_output_surface_);
   state->Set("minor_state", minor_state.release());
 
   return state.PassAs<base::Value>();
 }
 
-bool SchedulerStateMachine::HasDrawnAndSwappedThisFrame() const {
-  return current_frame_number_ == last_frame_number_swap_performed_;
+bool SchedulerStateMachine::HasSentBeginFrameToMainThreadThisFrame() const {
+  return begin_frame_count_ ==
+         last_begin_frame_count_begin_frame_sent_to_main_thread_;
 }
 
 bool SchedulerStateMachine::HasUpdatedVisibleTilesThisFrame() const {
-  return current_frame_number_ ==
-         last_frame_number_where_update_visible_tiles_was_called_;
+  return begin_frame_count_ ==
+         last_begin_frame_count_update_visible_tiles_was_called_;
 }
 
-bool SchedulerStateMachine::HasSentBeginFrameToMainThreadThisFrame() const {
-  return current_frame_number_ ==
-         last_frame_number_where_begin_frame_sent_to_main_thread_;
+bool SchedulerStateMachine::HasSwappedThisFrame() const {
+  return begin_frame_count_ == last_begin_frame_count_swap_performed_;
 }
 
 bool SchedulerStateMachine::PendingDrawsShouldBeAborted() const {
   // These are all the cases where we normally cannot or do not want to draw
   // but, if needs_redraw_ is true and we do not draw to make forward progress,
   // we might deadlock with the main thread.
   // This should be a superset of PendingActivationsShouldBeForced() since
   // activation of the pending tree is blocked by drawing of the active tree and
   // the main thread might be blocked on activation of the most recent commit.
   if (PendingActivationsShouldBeForced())
@@ skipping 62 matching lines @@
   }
 
   // If we need to abort draws, we should do so ASAP since the draw could
   // be blocking other important actions (like output surface initialization),
   // from occuring. If we are waiting for the first draw, then perfom the
   // aborted draw to keep things moving. If we are not waiting for the first
   // draw however, we don't want to abort for no reason.
   if (PendingDrawsShouldBeAborted())
     return active_tree_needs_first_draw_;
 
-  // After this line, we only want to draw once per frame.
-  if (HasDrawnAndSwappedThisFrame())
+  // After this line, we only want to swap once per frame.
+  if (HasSwappedThisFrame())
     return false;
 
-  // We currently only draw within the BeginFrame.
-  if (!inside_begin_frame_)
+  // Except for the cases above, do not draw outside of the BeginFrame deadline.
+  if (begin_frame_state_ != BEGIN_FRAME_STATE_INSIDE_DEADLINE)
     return false;
 
   // Only handle forced redraws due to timeouts on the regular deadline.
   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW) {
     DCHECK_EQ(commit_state_, COMMIT_STATE_WAITING_FOR_FIRST_DRAW);
     return true;
   }
 
   return needs_redraw_;
 }
@@ skipping 29 matching lines @@
 bool SchedulerStateMachine::ShouldUpdateVisibleTiles() const {
   if (!settings_.impl_side_painting)
     return false;
   if (HasUpdatedVisibleTilesThisFrame())
     return false;
 
   // There's no reason to check for tiles if we don't have an output surface.
   if (!HasInitializedOutputSurface())
     return false;
 
-  // We always want to update the most recent visible tiles before drawing
-  // so we draw with fewer missing tiles.
-  if (ShouldDraw())
-    return true;
+  // We should not check for visible tiles until we've entered the deadline so
+  // we check as late possible and give the tiles more time to initialize.
+  if (begin_frame_state_ != BEGIN_FRAME_STATE_INSIDE_DEADLINE)
+    return false;
 
   // If the last swap drew with checkerboard or missing tiles, we should
   // poll for any new visible tiles so we can be notified to draw again
   // when there are.
   if (swap_used_incomplete_tile_)
     return true;
 
   return false;
 }
 
@@ skipping 10 matching lines @@
     return false;
 
   // We want to handle readback commits immediately to unblock the main thread.
   // Note: This BeginFrame will correspond to the replacement commit that comes
   // after the readback commit itself, so we only send the BeginFrame if a
   // commit isn't already pending behind the readback.
   if (readback_state_ == READBACK_STATE_NEEDS_BEGIN_FRAME)
     return !CommitPending();
 
   // We do not need commits if we are not visible, unless there's a
-  // request for a forced commit.
+  // request for a readback.
   if (!visible_)
     return false;
 
+  // We shouldn't normally accept commits if there isn't an OutputSurface.
+  if (!HasInitializedOutputSurface())
+    return false;
+
   // We want to start the first commit after we get a new output surface ASAP.
   if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT)
     return true;
 
+  // We should not send the BeginFrame to the main thread while we are in
+  // BEGIN_FRAME_STATE_IDLE since we might have new user input coming in soon.
+  // TODO(brianderson): Also allow sending BeginFrame to main thread while idle
+  // when the main thread isn't consuming user input.
+  if (begin_frame_state_ == BEGIN_FRAME_STATE_IDLE)
+    return false;
+
   // We need a new commit for the forced redraw. This honors the
   // single commit per interval because the result will be swapped to screen.
   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT)
     return true;
 
   // After this point, we only start a commit once per frame.
   if (HasSentBeginFrameToMainThreadThisFrame())
     return false;
 
-  // We shouldn't normally accept commits if there isn't an OutputSurface.
-  if (!HasInitializedOutputSurface())
-    return false;
-
   return true;
 }
 
 bool SchedulerStateMachine::ShouldCommit() const {
   return commit_state_ == COMMIT_STATE_READY_TO_COMMIT;
 }
 
 SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
   if (ShouldAcquireLayerTexturesForMainThread())
     return ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD;
@@ skipping 26 matching lines @@
   DCHECK(!(forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW &&
            readback_state_ == READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK));
 }
 
 void SchedulerStateMachine::UpdateState(Action action) {
   switch (action) {
     case ACTION_NONE:
       return;
 
     case ACTION_UPDATE_VISIBLE_TILES:
-      last_frame_number_where_update_visible_tiles_was_called_ =
-          current_frame_number_;
+      last_begin_frame_count_update_visible_tiles_was_called_ =
+          begin_frame_count_;
       return;
 
     case ACTION_ACTIVATE_PENDING_TREE:
       UpdateStateOnActivation();
       return;
 
     case ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD:
       DCHECK(!has_pending_tree_);
       DCHECK(visible_ || readback_state_ == READBACK_STATE_NEEDS_BEGIN_FRAME);
       commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
       needs_commit_ = false;
       if (readback_state_ == READBACK_STATE_NEEDS_BEGIN_FRAME)
         readback_state_ = READBACK_STATE_WAITING_FOR_COMMIT;
-      last_frame_number_where_begin_frame_sent_to_main_thread_ =
-          current_frame_number_;
+      last_begin_frame_count_begin_frame_sent_to_main_thread_ =
+          begin_frame_count_;
       return;
 
     case ACTION_COMMIT: {
       bool commit_was_aborted = false;
       UpdateStateOnCommit(commit_was_aborted);
       return;
     }
 
     case ACTION_DRAW_AND_SWAP_FORCED:
     case ACTION_DRAW_AND_SWAP_IF_POSSIBLE: {
@@ skipping 92 matching lines @@
       (!commit_was_aborted ||
        readback_state_ == READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK ||
        forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)) {
     needs_redraw_ = true;
     active_tree_needs_first_draw_ = true;
   }
 
   // This post-commit work is common to both completed and aborted commits.
   pending_tree_is_ready_for_activation_ = false;
 
-  if (draw_if_possible_failed_)
-    last_frame_number_swap_performed_ = -1;
+  if (draw_if_possible_failed_) {
+    last_begin_frame_count_swap_performed_ = -1;
+  }
 
   // If we are planing to draw with the new commit, lock the layer textures for
   // use on the impl thread. Otherwise, leave them unlocked.
   if (has_pending_tree_ || needs_redraw_)
     texture_state_ = LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD;
   else
     texture_state_ = LAYER_TEXTURE_STATE_UNLOCKED;
 }
 
 void SchedulerStateMachine::UpdateStateOnActivation() {
@@ skipping 42 matching lines @@
   }
 
   if (texture_state_ == LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD)
     texture_state_ = LAYER_TEXTURE_STATE_UNLOCKED;
 
   needs_redraw_ = false;
   draw_if_possible_failed_ = false;
   active_tree_needs_first_draw_ = false;
 
   if (did_swap)
-    last_frame_number_swap_performed_ = current_frame_number_;
+    last_begin_frame_count_swap_performed_ = begin_frame_count_;
 }
 
 void SchedulerStateMachine::SetMainThreadNeedsLayerTextures() {
   DCHECK(!main_thread_needs_layer_textures_);
   DCHECK_NE(texture_state_, LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD);
   main_thread_needs_layer_textures_ = true;
 }
 
+bool SchedulerStateMachine::BeginFrameNeededByImplThread() const {
+  return BeginFrameNeededToDrawByImplThread() ||
+         ProactiveBeginFrameWantedByImplThread();
+}
+
 // These are the cases where we definitely (or almost definitely) have a
 // new frame to draw and can draw.
 bool SchedulerStateMachine::BeginFrameNeededToDrawByImplThread() const {
   // The output surface is the provider of BeginFrames for the impl thread,
   // so we are not going to get them even if we ask for them.
   if (!HasInitializedOutputSurface())
     return false;
 
   // If we can't draw, don't tick until we are notified that we can draw again.
   if (!can_draw_)
@@ skipping 14 matching lines @@
   if (swap_used_incomplete_tile_)
     return true;
 
   return needs_redraw_;
 }
 
 // These are cases where we are very likely to draw soon, but might not
 // actually have a new frame to draw when we receive the next BeginFrame.
 // Proactively requesting the BeginFrame helps hide the round trip latency of
 // the SetNeedsBeginFrame request that has to go to the Browser.
-// However, this is bad for the synchronous compositor because we have to
-// draw when we get the BeginFrame and could end up drawing many duplicate
-// frames.
 bool SchedulerStateMachine::ProactiveBeginFrameWantedByImplThread() const {
   // The output surface is the provider of BeginFrames for the impl thread,
   // so we are not going to get them even if we ask for them.
   if (!HasInitializedOutputSurface())
     return false;
 
+  // Proactive BeginFrames are bad for the synchronous compositor because we
+  // have to draw when we get the BeginFrame and could end up drawing many
+  // duplicate frames if our new frame isn't ready in time.
+  if (settings_.using_synchronous_renderer_compositor)
+    return false;
+
+  // Do not be proactive if vsync is off.
+  if (!settings_.throttle_frame_production)
+    return false;
+
   // Do not be proactive when invisible.
   if (!visible_)
     return false;
 
   // We should proactively request a BeginFrame if a commit is pending
   // because we will want to draw if the commit completes quickly.
   if (needs_commit_ || commit_state_ != COMMIT_STATE_IDLE)
     return true;
 
   // If the pending tree activates quickly, we'll want a BeginFrame soon
   // to draw the new active tree.
   if (has_pending_tree_)
     return true;
 
   return false;
 }
 
-void SchedulerStateMachine::DidEnterBeginFrame(const BeginFrameArgs& args) {
-  current_frame_number_++;
-  inside_begin_frame_ = true;
+void SchedulerStateMachine::OnBeginFrame(const BeginFrameArgs& args) {
+  begin_frame_count_++;
   last_begin_frame_args_ = args;
+  DCHECK_EQ(begin_frame_state_, BEGIN_FRAME_STATE_IDLE)
+    << *AsValue();
+  begin_frame_state_ = BEGIN_FRAME_STATE_INSIDE_BEGIN_FRAME;
 }
 
-void SchedulerStateMachine::DidLeaveBeginFrame() {
-  inside_begin_frame_ = false;
+void SchedulerStateMachine::OnBeginFrameDeadlinePending() {

[enne (OOO), 2013/09/11 22:30:47]

These functions make things a lot more clear!

+  DCHECK_EQ(begin_frame_state_, BEGIN_FRAME_STATE_INSIDE_BEGIN_FRAME)
+      << *AsValue();
+  begin_frame_state_ = BEGIN_FRAME_STATE_DEADLINE_PENDING;
+}
+
+void SchedulerStateMachine::OnBeginFrameDeadline() {
+  DCHECK_EQ(begin_frame_state_, BEGIN_FRAME_STATE_DEADLINE_PENDING)
+    << *AsValue();
+  begin_frame_state_ = BEGIN_FRAME_STATE_INSIDE_DEADLINE;
+}
+
+void SchedulerStateMachine::OnBeginFrameIdle() {
+  if (HasInitializedOutputSurface()) {
+    DCHECK_EQ(begin_frame_state_, BEGIN_FRAME_STATE_INSIDE_DEADLINE)
+        << *AsValue();
+  }
+  begin_frame_state_ = BEGIN_FRAME_STATE_IDLE;
+}
+
+bool SchedulerStateMachine::ShouldTriggerBeginFrameDeadlineEarly() const {
+  // TODO(brianderson): This should take into account multiple commit sources.
+  return begin_frame_state_ == BEGIN_FRAME_STATE_DEADLINE_PENDING &&
+         active_tree_needs_first_draw_;
+}
+
+bool SchedulerStateMachine::InsideBeginFrame() const {

[enne (OOO), 2013/09/11 22:30:47]

What does "inside begin frame" mean here if this function is also true for the
deadline pending case?

[brianderson, 2013/09/12 00:12:34]

I'll need to fix the naming. "Inside BeginFrame" is clearly an overloaded term.

+  return begin_frame_state_ == BEGIN_FRAME_STATE_INSIDE_BEGIN_FRAME ||
+         begin_frame_state_ == BEGIN_FRAME_STATE_DEADLINE_PENDING;
 }
 
 void SchedulerStateMachine::SetVisible(bool visible) { visible_ = visible; }
 
+void SchedulerStateMachine::SetCanDraw(bool can_draw) { can_draw_ = can_draw; }
+
 void SchedulerStateMachine::SetNeedsRedraw() { needs_redraw_ = true; }
 
 void SchedulerStateMachine::SetSwapUsedIncompleteTile(
     bool used_incomplete_tile) {
   swap_used_incomplete_tile_ = used_incomplete_tile;
 }
 
 void SchedulerStateMachine::DidDrawIfPossibleCompleted(bool success) {
   draw_if_possible_failed_ = !success;
   if (draw_if_possible_failed_) {
@@ skipping 52 matching lines @@
     SetNeedsCommit();
   }
 }
 
 void SchedulerStateMachine::DidLoseOutputSurface() {
   if (output_surface_state_ == OUTPUT_SURFACE_LOST ||
       output_surface_state_ == OUTPUT_SURFACE_CREATING)
     return;
   output_surface_state_ = OUTPUT_SURFACE_LOST;
   needs_redraw_ = false;
+  begin_frame_state_ = BEGIN_FRAME_STATE_IDLE;
 }
 
 void SchedulerStateMachine::NotifyReadyToActivate() {
   if (has_pending_tree_)
     pending_tree_is_ready_for_activation_ = true;
 }
 
-void SchedulerStateMachine::SetCanDraw(bool can) { can_draw_ = can; }
-
 void SchedulerStateMachine::DidCreateAndInitializeOutputSurface() {
   DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_CREATING);
   output_surface_state_ = OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT;
 
   if (did_create_and_initialize_first_output_surface_) {
     // TODO(boliu): See if we can remove this when impl-side painting is always
     // on. Does anything on the main thread need to update after recreate?
     needs_commit_ = true;
   }
   did_create_and_initialize_first_output_surface_ = true;
 }
 
 bool SchedulerStateMachine::HasInitializedOutputSurface() const {
   switch (output_surface_state_) {
     case OUTPUT_SURFACE_LOST:
     case OUTPUT_SURFACE_CREATING:
       return false;
 
     case OUTPUT_SURFACE_ACTIVE:
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
     case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
       return true;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace cc