Remove forced commit and readback from the scheduler.

This removes CompositeAndReadback support from the scheduler, since the
code path is now removed.

R=brianderson
BUG=251936

Review URL: https://codereview.chromium.org/292533002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271722 0039d316-1c4b-4281-b951-d872f2087c98

cc/scheduler/draw_result.h

@@ -12,8 +12,6 @@ enum DrawResult {
   DRAW_SUCCESS,
   DRAW_ABORTED_CHECKERBOARD_ANIMATIONS,
   DRAW_ABORTED_MISSING_HIGH_RES_CONTENT,
-  // TODO(danakj): Remove this.
-  DRAW_ABORTED_CANT_READBACK,
   DRAW_ABORTED_CONTEXT_LOST,
   DRAW_ABORTED_CANT_DRAW,
 };

cc/scheduler/scheduler.cc

@@ -164,11 +164,6 @@ void Scheduler::SetNeedsCommit() {
   ProcessScheduledActions();
 }
 
-void Scheduler::SetNeedsForcedCommitForReadback() {
-  state_machine_.SetNeedsForcedCommitForReadback();
-  ProcessScheduledActions();
-}
-
 void Scheduler::SetNeedsRedraw() {
   state_machine_.SetNeedsRedraw();
   ProcessScheduledActions();
@@ -192,9 +187,6 @@ void Scheduler::SetMaxSwapsPending(int max) {
 void Scheduler::DidSwapBuffers() {
   state_machine_.DidSwapBuffers();
 
-  // Swap should not occur inside readback operation.
-  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_) {
@@ -618,7 +610,6 @@ void Scheduler::ProcessScheduledActions() {
 
   SchedulerStateMachine::Action action;
   do {
-    state_machine_.CheckInvariants();
     action = state_machine_.NextAction();
     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
                  "SchedulerStateMachine",
@@ -655,9 +646,6 @@ void Scheduler::ProcessScheduledActions() {
         // 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();
-        break;
       case SchedulerStateMachine::ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
         client_->ScheduledActionBeginOutputSurfaceCreation();
         break;

cc/scheduler/scheduler.h

@@ -32,7 +32,6 @@ class SchedulerClient {
   virtual void ScheduledActionSendBeginMainFrame() = 0;
   virtual DrawResult ScheduledActionDrawAndSwapIfPossible() = 0;
   virtual DrawResult ScheduledActionDrawAndSwapForced() = 0;
-  virtual DrawResult ScheduledActionDrawAndReadback() = 0;
   virtual void ScheduledActionAnimate() = 0;
   virtual void ScheduledActionCommit() = 0;
   virtual void ScheduledActionUpdateVisibleTiles() = 0;
@@ -76,10 +75,6 @@ class CC_EXPORT Scheduler {
 
   void SetNeedsCommit();
 
-  // Like SetNeedsCommit(), but ensures a commit will definitely happen even if
-  // we are not visible. Will eventually result in a forced draw internally.
-  void SetNeedsForcedCommitForReadback();
-
   void SetNeedsRedraw();
 
   void SetNeedsAnimate();

cc/scheduler/scheduler_state_machine.h

@@ -68,18 +68,6 @@ class CC_EXPORT SchedulerStateMachine {
   };
   static const char* CommitStateToString(CommitState state);
 
-  enum SynchronousReadbackState {
-    READBACK_STATE_IDLE,
-    READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME,
-    READBACK_STATE_WAITING_FOR_COMMIT,
-    READBACK_STATE_WAITING_FOR_ACTIVATION,
-    READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK,
-    READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT,
-    READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION,
-  };
-  static const char* SynchronousReadbackStateToString(
-      SynchronousReadbackState state);
-
   enum ForcedRedrawOnTimeoutState {
     FORCED_REDRAW_STATE_IDLE,
     FORCED_REDRAW_STATE_WAITING_FOR_COMMIT,
@@ -109,7 +97,6 @@ class CC_EXPORT SchedulerStateMachine {
     ACTION_DRAW_AND_SWAP_IF_POSSIBLE,
     ACTION_DRAW_AND_SWAP_FORCED,
     ACTION_DRAW_AND_SWAP_ABORT,
-    ACTION_DRAW_AND_READBACK,
     ACTION_BEGIN_OUTPUT_SURFACE_CREATION,
     ACTION_MANAGE_TILES,
   };
@@ -120,8 +107,6 @@ class CC_EXPORT SchedulerStateMachine {
   Action NextAction() const;
   void UpdateState(Action action);
 
-  void CheckInvariants();
-
   // Indicates whether the impl thread needs a BeginImplFrame callback in order
   // to make progress.
   bool BeginFrameNeeded() const;
@@ -200,12 +185,6 @@ class CC_EXPORT SchedulerStateMachine {
   // thread to main.
   void SetNeedsCommit();
 
-  // As SetNeedsCommit(), but ensures the BeginMainFrame will be sent even
-  // if we are not visible.  After this call we expect to go through
-  // the forced commit flow and then return to waiting for a non-forced
-  // BeginMainFrame to finish.
-  void SetNeedsForcedCommitForReadback();
-
   // Call this only in response to receiving an ACTION_SEND_BEGIN_MAIN_FRAME
   // from NextAction.
   // Indicates that all painting is complete.
@@ -285,7 +264,6 @@ class CC_EXPORT SchedulerStateMachine {
   BeginImplFrameState begin_impl_frame_state_;
   CommitState commit_state_;
   ForcedRedrawOnTimeoutState forced_redraw_state_;
-  SynchronousReadbackState readback_state_;
 
   BeginFrameArgs begin_impl_frame_args_;
 
@@ -322,7 +300,6 @@ class CC_EXPORT SchedulerStateMachine {
   bool skip_next_begin_main_frame_to_reduce_latency_;
   bool skip_begin_main_frame_to_reduce_latency_;
   bool continuous_painting_;
-  bool needs_back_to_back_readback_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SchedulerStateMachine);

cc/scheduler/scheduler_unittest.cc

@@ -134,11 +134,6 @@ class FakeSchedulerClient : public SchedulerClient {
     states_.push_back(scheduler_->AsValue().release());
     return DRAW_SUCCESS;
   }
-  virtual DrawResult ScheduledActionDrawAndReadback() OVERRIDE {
-    actions_.push_back("ScheduledActionDrawAndReadback");
-    states_.push_back(scheduler_->AsValue().release());
-    return DRAW_SUCCESS;
-  }
   virtual void ScheduledActionCommit() OVERRIDE {
     actions_.push_back("ScheduledActionCommit");
     states_.push_back(scheduler_->AsValue().release());
@@ -645,53 +640,6 @@ TEST(SchedulerTest, NoSwapWhenDrawFails) {
   EXPECT_EQ(2, client.num_draws());
 }
 
-TEST(SchedulerTest, NoSwapWhenSwapFailsDuringForcedCommit) {
-  FakeSchedulerClient client;
-  SchedulerSettings default_scheduler_settings;
-  Scheduler* scheduler = client.CreateScheduler(default_scheduler_settings);
-
-  // Tell the client that it will fail to swap.
-  client.SetDrawWillHappen(true);
-  client.SetSwapWillHappenIfDrawHappens(false);
-
-  // Get the compositor to do a ScheduledActionDrawAndReadback.
-  scheduler->SetCanDraw(true);
-  scheduler->SetNeedsRedraw();
-  scheduler->SetNeedsForcedCommitForReadback();
-  scheduler->NotifyBeginMainFrameStarted();
-  scheduler->NotifyReadyToCommit();
-  EXPECT_TRUE(client.HasAction("ScheduledActionDrawAndReadback"));
-}
-
-TEST(SchedulerTest, BackToBackReadbackAllowed) {
-  // Some clients call readbacks twice in a row before the replacement
-  // commit comes in.  Make sure it is allowed.
-  FakeSchedulerClient client;
-  SchedulerSettings default_scheduler_settings;
-  Scheduler* scheduler = client.CreateScheduler(default_scheduler_settings);
-
-  // Get the compositor to do 2 ScheduledActionDrawAndReadbacks before
-  // the replacement commit comes in.
-  scheduler->SetCanDraw(true);
-  scheduler->SetNeedsRedraw();
-  scheduler->SetNeedsForcedCommitForReadback();
-  scheduler->NotifyBeginMainFrameStarted();
-  scheduler->NotifyReadyToCommit();
-  EXPECT_TRUE(client.HasAction("ScheduledActionDrawAndReadback"));
-
-  client.Reset();
-  scheduler->SetNeedsForcedCommitForReadback();
-  scheduler->NotifyBeginMainFrameStarted();
-  scheduler->NotifyReadyToCommit();
-  EXPECT_TRUE(client.HasAction("ScheduledActionDrawAndReadback"));
-
-  // The replacement commit comes in after 2 readbacks.
-  client.Reset();
-  scheduler->NotifyBeginMainFrameStarted();
-  scheduler->NotifyReadyToCommit();
-}
-
-
 class SchedulerClientNeedsManageTilesInDraw : public FakeSchedulerClient {
  public:
   virtual DrawResult ScheduledActionDrawAndSwapIfPossible()

cc/trees/thread_proxy.cc

@@ -1149,12 +1149,6 @@ DrawResult ThreadProxy::ScheduledActionDrawAndSwapForced() {
   return DrawSwapInternal(forced_draw);
 }
 
-DrawResult ThreadProxy::ScheduledActionDrawAndReadback() {
-  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionDrawAndReadback");
-  NOTREACHED();
-  return INVALID_RESULT;
-}
-
 void ThreadProxy::DidAnticipatedDrawTimeChange(base::TimeTicks time) {
   if (impl().current_resource_update_controller)
     impl().current_resource_update_controller->PerformMoreUpdates(time);

cc/trees/thread_proxy.h

@@ -110,7 +110,6 @@ class ThreadProxy : public Proxy,
   virtual void ScheduledActionSendBeginMainFrame() OVERRIDE;
   virtual DrawResult ScheduledActionDrawAndSwapIfPossible() OVERRIDE;
   virtual DrawResult ScheduledActionDrawAndSwapForced() OVERRIDE;
-  virtual DrawResult ScheduledActionDrawAndReadback() OVERRIDE;
   virtual void ScheduledActionAnimate() OVERRIDE;
   virtual void ScheduledActionCommit() OVERRIDE;
   virtual void ScheduledActionUpdateVisibleTiles() OVERRIDE;