cc: Make scheduling be driven by vsync for android webview.

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/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "base/values.h"
 #include "ui/gfx/frame_time.h"
 
 namespace cc {
 
 SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
     : settings_(settings),
       output_surface_state_(OUTPUT_SURFACE_LOST),
       begin_impl_frame_state_(BEGIN_IMPL_FRAME_STATE_IDLE),
       commit_state_(COMMIT_STATE_IDLE),
       forced_redraw_state_(FORCED_REDRAW_STATE_IDLE),
       commit_count_(0),
       current_frame_number_(0),
       last_frame_number_animate_performed_(-1),
       last_frame_number_swap_performed_(-1),
       last_frame_number_swap_requested_(-1),
       last_frame_number_begin_main_frame_sent_(-1),
+      last_frame_number_invalidate_output_surface_performed_(-1),
       animate_funnel_(false),
-      perform_swap_funnel_(false),
       request_swap_funnel_(false),
       send_begin_main_frame_funnel_(false),
+      invalidate_output_surface_funnel_(false),
       prepare_tiles_funnel_(0),
       consecutive_checkerboard_animations_(0),
       max_pending_swaps_(1),
       pending_swaps_(0),
       needs_redraw_(false),
       needs_animate_(false),
       needs_prepare_tiles_(false),
       needs_commit_(false),
-      inside_poll_for_anticipated_draw_triggers_(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),
       did_create_and_initialize_first_output_surface_(false),
       impl_latency_takes_priority_(false),
       skip_next_begin_main_frame_to_reduce_latency_(false),
       skip_begin_main_frame_to_reduce_latency_(false),
       continuous_painting_(false),
       children_need_begin_frames_(false),
       defer_commits_(false),
-      last_commit_had_no_updates_(false) {
+      last_commit_had_no_updates_(false),
+      did_request_swap_in_last_frame_(false),
+      did_perform_swap_in_last_draw_(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:
@@ skipping 16 matching lines @@
       return "BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING";
     case BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME:
       return "BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME";
     case BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE:
       return "BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE";
   }
   NOTREACHED();
   return "???";
 }
 
+const char* SchedulerStateMachine::BeginImplFrameDeadlineModeToString(
+    BeginImplFrameDeadlineMode mode) {
+  switch (mode) {
+    case BEGIN_IMPL_FRAME_DEADLINE_MODE_NONE:
+      return "BEGIN_IMPL_FRAME_DEADLINE_MODE_NONE";
+    case BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE:
+      return "BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE";
+    case BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR:
+      return "BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR";
+    case BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE:
+      return "BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE";
+  }
+  NOTREACHED();
+  return "???";
+}
+
 const char* SchedulerStateMachine::CommitStateToString(CommitState state) {
   switch (state) {
     case COMMIT_STATE_IDLE:
       return "COMMIT_STATE_IDLE";
     case COMMIT_STATE_BEGIN_MAIN_FRAME_SENT:
       return "COMMIT_STATE_BEGIN_MAIN_FRAME_SENT";
     case COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED:
       return "COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED";
     case COMMIT_STATE_READY_TO_COMMIT:
       return "COMMIT_STATE_READY_TO_COMMIT";
@@ skipping 37 matching lines @@
     case ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
       return "ACTION_DRAW_AND_SWAP_IF_POSSIBLE";
     case ACTION_DRAW_AND_SWAP_FORCED:
       return "ACTION_DRAW_AND_SWAP_FORCED";
     case ACTION_DRAW_AND_SWAP_ABORT:
       return "ACTION_DRAW_AND_SWAP_ABORT";
     case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
       return "ACTION_BEGIN_OUTPUT_SURFACE_CREATION";
     case ACTION_PREPARE_TILES:
       return "ACTION_PREPARE_TILES";
+    case ACTION_INVALIDATE_OUTPUT_SURFACE:
+      return "ACTION_INVALIDATE_OUTPUT_SURFACE";
   }
   NOTREACHED();
   return "???";
 }
 
 scoped_refptr<base::trace_event::ConvertableToTraceFormat>
 SchedulerStateMachine::AsValue() const {
   scoped_refptr<base::trace_event::TracedValue> state =
       new base::trace_event::TracedValue();
   AsValueInto(state.get());
@@ skipping 18 matching lines @@
   state->SetInteger("current_frame_number", current_frame_number_);
   state->SetInteger("last_frame_number_animate_performed",
                     last_frame_number_animate_performed_);
   state->SetInteger("last_frame_number_swap_performed",
                     last_frame_number_swap_performed_);
   state->SetInteger("last_frame_number_swap_requested",
                     last_frame_number_swap_requested_);
   state->SetInteger("last_frame_number_begin_main_frame_sent",
                     last_frame_number_begin_main_frame_sent_);
   state->SetBoolean("funnel: animate_funnel", animate_funnel_);
-  state->SetBoolean("funnel: perform_swap_funnel", perform_swap_funnel_);
   state->SetBoolean("funnel: request_swap_funnel", request_swap_funnel_);
   state->SetBoolean("funnel: send_begin_main_frame_funnel",
                     send_begin_main_frame_funnel_);
   state->SetInteger("funnel: prepare_tiles_funnel", prepare_tiles_funnel_);
+  state->SetBoolean("funnel: invalidate_output_surface_funnel",
+                    invalidate_output_surface_funnel_);
   state->SetInteger("consecutive_checkerboard_animations",
                     consecutive_checkerboard_animations_);
   state->SetInteger("max_pending_swaps_", max_pending_swaps_);
   state->SetInteger("pending_swaps_", pending_swaps_);
   state->SetBoolean("needs_redraw", needs_redraw_);
   state->SetBoolean("needs_animate_", needs_animate_);
   state->SetBoolean("needs_prepare_tiles", needs_prepare_tiles_);
   state->SetBoolean("needs_commit", needs_commit_);
   state->SetBoolean("visible", visible_);
   state->SetBoolean("can_start", can_start_);
   state->SetBoolean("can_draw", can_draw_);
   state->SetBoolean("has_pending_tree", has_pending_tree_);
   state->SetBoolean("pending_tree_is_ready_for_activation",
                     pending_tree_is_ready_for_activation_);
   state->SetBoolean("active_tree_needs_first_draw",
                     active_tree_needs_first_draw_);
   state->SetBoolean("did_create_and_initialize_first_output_surface",
                     did_create_and_initialize_first_output_surface_);
   state->SetBoolean("impl_latency_takes_priority",
                     impl_latency_takes_priority_);
   state->SetBoolean("main_thread_is_in_high_latency_mode",
                     MainThreadIsInHighLatencyMode());
   state->SetBoolean("skip_begin_main_frame_to_reduce_latency",
                     skip_begin_main_frame_to_reduce_latency_);
   state->SetBoolean("skip_next_begin_main_frame_to_reduce_latency",
                     skip_next_begin_main_frame_to_reduce_latency_);
   state->SetBoolean("continuous_painting", continuous_painting_);
   state->SetBoolean("children_need_begin_frames", children_need_begin_frames_);
   state->SetBoolean("defer_commits", defer_commits_);
+  state->SetBoolean("last_commit_had_no_updates", last_commit_had_no_updates_);
+  state->SetBoolean("did_request_swap_in_last_frame",
+                    did_request_swap_in_last_frame_);
+  state->SetBoolean("did_perform_swap_in_last_draw",
+                    did_perform_swap_in_last_draw_);
   state->EndDictionary();
 }
 
-void SchedulerStateMachine::AdvanceCurrentFrameNumber() {
-  current_frame_number_++;
-
-  animate_funnel_ = false;
-  perform_swap_funnel_ = false;
-  request_swap_funnel_ = false;
-  send_begin_main_frame_funnel_ = false;
-
-  // "Drain" the PrepareTiles funnel.
-  if (prepare_tiles_funnel_ > 0)
-    prepare_tiles_funnel_--;
-
-  skip_begin_main_frame_to_reduce_latency_ =
-      skip_next_begin_main_frame_to_reduce_latency_;
-  skip_next_begin_main_frame_to_reduce_latency_ = false;
-}
-
 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())
     return true;
 
@@ skipping 169 matching lines @@
     return true;
 
   // We shouldn't normally accept commits if there isn't an OutputSurface.
   if (!HasInitializedOutputSurface())
     return false;
 
   // SwapAck throttle the BeginMainFrames unless we just swapped.
   // TODO(brianderson): Remove this restriction to improve throughput.
   bool just_swapped_in_deadline =
       begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE &&
-      perform_swap_funnel_;
+      did_perform_swap_in_last_draw_;
   if (pending_swaps_ >= max_pending_swaps_ && !just_swapped_in_deadline)
     return false;
 
   if (skip_begin_main_frame_to_reduce_latency_)
     return false;
 
   return true;
 }
 
 bool SchedulerStateMachine::ShouldCommit() const {
@@ skipping 14 matching lines @@
 }
 
 bool SchedulerStateMachine::ShouldPrepareTiles() const {
   // PrepareTiles only really needs to be called immediately after commit
   // and then periodically after that. Use a funnel to make sure we average
   // one PrepareTiles per BeginImplFrame in the long run.
   if (prepare_tiles_funnel_ > 0)
     return false;
 
   // Limiting to once per-frame is not enough, since we only want to
-  // prepare tiles _after_ draws. Polling for draw triggers and
-  // begin-frame are mutually exclusive, so we limit to these two cases.
-  if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE &&
-      !inside_poll_for_anticipated_draw_triggers_)
+  // prepare tiles _after_ draws.
+  if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
     return false;
+
   return needs_prepare_tiles_;
 }
 
+bool SchedulerStateMachine::ShouldInvalidateOutputSurface() const {
+  // Do not invalidate too many times in a frame.
+  if (invalidate_output_surface_funnel_)
+    return false;
+
+  // Only the synchronous compositor requires invalidations.
+  if (!settings_.using_synchronous_renderer_compositor)
+    return false;
+
+  // Invalidations are only performed inside a BeginFrame.
+  if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING)
+    return false;
+
+  return needs_redraw_ || needs_prepare_tiles_;

[brianderson, 2015/04/01 00:23:38]

Can you add a TODO explaining what would need to happen to remove
needs_prepare_tiles_ here?

[sunnyps, 2015/04/01 19:53:01]

Done.

+}
+
 SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
   if (ShouldActivatePendingTree())
     return ACTION_ACTIVATE_SYNC_TREE;
   if (ShouldCommit())
     return ACTION_COMMIT;
   if (ShouldAnimate())
     return ACTION_ANIMATE;
   if (ShouldDraw()) {
     if (PendingDrawsShouldBeAborted())
       return ACTION_DRAW_AND_SWAP_ABORT;
     else if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
       return ACTION_DRAW_AND_SWAP_FORCED;
     else
       return ACTION_DRAW_AND_SWAP_IF_POSSIBLE;
   }
   if (ShouldPrepareTiles())
     return ACTION_PREPARE_TILES;
   if (ShouldSendBeginMainFrame())
     return ACTION_SEND_BEGIN_MAIN_FRAME;
+  if (ShouldInvalidateOutputSurface())
+    return ACTION_INVALIDATE_OUTPUT_SURFACE;
   if (ShouldBeginOutputSurfaceCreation())
     return ACTION_BEGIN_OUTPUT_SURFACE_CREATION;
   return ACTION_NONE;
 }
 
 void SchedulerStateMachine::UpdateState(Action action) {
   switch (action) {
     case ACTION_NONE:
       return;
 
     case ACTION_ACTIVATE_SYNC_TREE:
       UpdateStateOnActivation();
       return;
 
     case ACTION_ANIMATE:
-      DCHECK(!animate_funnel_);
-      last_frame_number_animate_performed_ = current_frame_number_;
-      animate_funnel_ = true;
-      needs_animate_ = false;
-      // TODO(skyostil): Instead of assuming this, require the client to tell
-      // us.
-      SetNeedsRedraw();
+      UpdateStateOnAnimate();
       return;
 
     case ACTION_SEND_BEGIN_MAIN_FRAME:
-      DCHECK(!has_pending_tree_ ||
-             settings_.main_frame_before_activation_enabled);
-      DCHECK(visible_);
-      DCHECK(!send_begin_main_frame_funnel_);
-      commit_state_ = COMMIT_STATE_BEGIN_MAIN_FRAME_SENT;
-      needs_commit_ = false;
-      send_begin_main_frame_funnel_ = true;
-      last_frame_number_begin_main_frame_sent_ =
-          current_frame_number_;
+      UpdateStateOnSendBeginMainFrame();
       return;
 
     case ACTION_COMMIT: {
       bool commit_has_no_updates = false;
       UpdateStateOnCommit(commit_has_no_updates);
       return;
     }
 
     case ACTION_DRAW_AND_SWAP_FORCED:
     case ACTION_DRAW_AND_SWAP_IF_POSSIBLE: {
       bool did_request_swap = true;
       UpdateStateOnDraw(did_request_swap);
       return;
     }
 
     case ACTION_DRAW_AND_SWAP_ABORT: {
       bool did_request_swap = false;
       UpdateStateOnDraw(did_request_swap);
       return;
     }
 
     case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
-      DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_LOST);
-      output_surface_state_ = OUTPUT_SURFACE_CREATING;
-
-      // The following DCHECKs make sure we are in the proper quiescent state.
-      // The pipeline should be flushed entirely before we start output
-      // surface creation to avoid complicated corner cases.
-      DCHECK_EQ(commit_state_, COMMIT_STATE_IDLE);
-      DCHECK(!has_pending_tree_);
-      DCHECK(!active_tree_needs_first_draw_);
+      UpdateStateOnBeginOutputSurfaceCreation();
       return;
 
     case ACTION_PREPARE_TILES:
       UpdateStateOnPrepareTiles();
       return;
+
+    case ACTION_INVALIDATE_OUTPUT_SURFACE:
+      UpdateStateOnInvalidateOutputSurface();
+      return;
   }
 }
 
+void SchedulerStateMachine::UpdateStateOnAnimate() {
+  DCHECK(!animate_funnel_);
+  last_frame_number_animate_performed_ = current_frame_number_;
+  animate_funnel_ = true;
+  needs_animate_ = false;
+  // TODO(skyostil): Instead of assuming this, require the client to tell us.
+  SetNeedsRedraw();
+}
+
+void SchedulerStateMachine::UpdateStateOnSendBeginMainFrame() {
+  DCHECK(!has_pending_tree_ || settings_.main_frame_before_activation_enabled);
+  DCHECK(visible_);
+  DCHECK(!send_begin_main_frame_funnel_);
+  commit_state_ = COMMIT_STATE_BEGIN_MAIN_FRAME_SENT;
+  needs_commit_ = false;
+  send_begin_main_frame_funnel_ = true;
+  last_frame_number_begin_main_frame_sent_ = current_frame_number_;
+}
+
 void SchedulerStateMachine::UpdateStateOnCommit(bool commit_has_no_updates) {
   commit_count_++;
 
+  // Animate after commit even if we've already animated.
   if (!commit_has_no_updates)
     animate_funnel_ = false;
 
   if (commit_has_no_updates || settings_.main_frame_before_activation_enabled) {
     commit_state_ = COMMIT_STATE_IDLE;
   } else if (settings_.impl_side_painting) {
     commit_state_ = COMMIT_STATE_WAITING_FOR_ACTIVATION;
   } else {
     commit_state_ = settings_.main_thread_should_always_be_low_latency
                         ? COMMIT_STATE_WAITING_FOR_DRAW
@@ skipping 64 matching lines @@
 
   if (commit_state_ == COMMIT_STATE_WAITING_FOR_DRAW)
     commit_state_ = COMMIT_STATE_IDLE;
 
   needs_redraw_ = false;
   active_tree_needs_first_draw_ = false;
 
   if (did_request_swap) {
     DCHECK(!request_swap_funnel_);
     request_swap_funnel_ = true;
+    did_request_swap_in_last_frame_ = true;
     last_frame_number_swap_requested_ = current_frame_number_;
   }
 }
 
 void SchedulerStateMachine::UpdateStateOnPrepareTiles() {
   needs_prepare_tiles_ = false;
 }
 
+void SchedulerStateMachine::UpdateStateOnBeginOutputSurfaceCreation() {
+  DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_LOST);
+  output_surface_state_ = OUTPUT_SURFACE_CREATING;
+
+  // The following DCHECKs make sure we are in the proper quiescent state.
+  // The pipeline should be flushed entirely before we start output
+  // surface creation to avoid complicated corner cases.
+  DCHECK_EQ(commit_state_, COMMIT_STATE_IDLE);
+  DCHECK(!has_pending_tree_);
+  DCHECK(!active_tree_needs_first_draw_);
+}
+
+void SchedulerStateMachine::UpdateStateOnInvalidateOutputSurface() {
+  DCHECK(!invalidate_output_surface_funnel_);
+  invalidate_output_surface_funnel_ = true;
+  last_frame_number_invalidate_output_surface_performed_ =
+      current_frame_number_;
+}
+
 void SchedulerStateMachine::SetSkipNextBeginMainFrameToReduceLatency() {
   TRACE_EVENT_INSTANT0("cc",
                        "Scheduler: SkipNextBeginMainFrameToReduceLatency",
                        TRACE_EVENT_SCOPE_THREAD);
   skip_next_begin_main_frame_to_reduce_latency_ = true;
 }
 
 bool SchedulerStateMachine::BeginFrameNeededForChildren() const {
-  if (HasInitializedOutputSurface())
-    return children_need_begin_frames_;
-
-  return false;
+  return children_need_begin_frames_;
 }
 
 bool SchedulerStateMachine::BeginFrameNeeded() const {
   // We can't handle BeginFrames when output surface isn't initialized.
   // TODO(brianderson): Support output surface creation inside a BeginFrame.
   if (!HasInitializedOutputSurface())
     return false;
-
-  if (SupportsProactiveBeginFrame()) {
-    return (BeginFrameNeededToAnimateOrDraw() ||
-            BeginFrameNeededForChildren() ||
-            ProactiveBeginFrameWanted());
-  }
-
-  // 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.
-  // To poll for state with the synchronous compositor without having to draw,
-  // we rely on ShouldPollForAnticipatedDrawTriggers instead.
-  // Synchronous compositor doesn't have a browser.
-  DCHECK(!children_need_begin_frames_);
-  return BeginFrameNeededToAnimateOrDraw();
-}
-
-bool SchedulerStateMachine::ShouldPollForAnticipatedDrawTriggers() const {
-  // ShouldPollForAnticipatedDrawTriggers is what we use in place of
-  // ProactiveBeginFrameWanted when we are using the synchronous
-  // compositor.
-  if (!SupportsProactiveBeginFrame()) {
-    return !BeginFrameNeededToAnimateOrDraw() && ProactiveBeginFrameWanted();
-  }
-
-  // Non synchronous compositors should rely on
-  // ProactiveBeginFrameWanted to poll for state instead.
-  return false;
-}
-
-// Note: If SupportsProactiveBeginFrame is false, the scheduler should poll
-// for changes in it's draw state so it can request a BeginFrame when it's
-// actually ready.
-bool SchedulerStateMachine::SupportsProactiveBeginFrame() const {
-  // It is undesirable to proactively request BeginFrames if we are
-  // using a synchronous compositor because we *must* draw for every
-  // BeginFrame, which could cause duplicate draws.
-  return !settings_.using_synchronous_renderer_compositor;
+  return (BeginFrameNeededToAnimateOrDraw() || BeginFrameNeededForChildren() ||
+          ProactiveBeginFrameWanted());
 }
 
 void SchedulerStateMachine::SetChildrenNeedBeginFrames(
     bool children_need_begin_frames) {
   children_need_begin_frames_ = children_need_begin_frames;
 }
 
 void SchedulerStateMachine::SetDeferCommits(bool defer_commits) {
   defer_commits_ = defer_commits;
 }
@@ skipping 31 matching lines @@
   // Changing priorities may allow us to activate (given the new priorities),
   // which may result in a new frame.
   if (needs_prepare_tiles_)
     return true;
 
   // If we just sent a swap request, it's likely that we are going to produce
   // another frame soon. This helps avoid negative glitches in our
   // SetNeedsBeginFrame requests, which may propagate to the BeginImplFrame
   // provider and get sampled at an inopportune time, delaying the next
   // BeginImplFrame.
-  if (request_swap_funnel_)
+  if (did_request_swap_in_last_frame_)
     return true;
 
   // If the last commit was aborted because of early out (no updates), we should
   // still want a begin frame in case there is a commit coming again.
   if (last_commit_had_no_updates_)
     return true;
 
   return false;
 }
 
 void SchedulerStateMachine::OnBeginImplFrame() {
-  AdvanceCurrentFrameNumber();
-  DCHECK_EQ(begin_impl_frame_state_, BEGIN_IMPL_FRAME_STATE_IDLE)
-      << AsValue()->ToString();
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING;
+  current_frame_number_++;
+
   last_commit_had_no_updates_ = false;
+  did_request_swap_in_last_frame_ = false;
+
+  // Clear funnels for any actions we perform during the frame.
+  animate_funnel_ = false;
+  send_begin_main_frame_funnel_ = false;
+  invalidate_output_surface_funnel_ = false;
+
+  // "Drain" the PrepareTiles funnel.
+  if (prepare_tiles_funnel_ > 0)
+    prepare_tiles_funnel_--;
+
+  skip_begin_main_frame_to_reduce_latency_ =
+      skip_next_begin_main_frame_to_reduce_latency_;
+  skip_next_begin_main_frame_to_reduce_latency_ = false;
 }
 
 void SchedulerStateMachine::OnBeginImplFrameDeadlinePending() {
-  DCHECK_EQ(begin_impl_frame_state_,
-            BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING)
-      << AsValue()->ToString();
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME;
 }
 
 void SchedulerStateMachine::OnBeginImplFrameDeadline() {
-  DCHECK_EQ(begin_impl_frame_state_, BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
-      << AsValue()->ToString();
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
+
+  did_perform_swap_in_last_draw_ = false;
+
+  // Clear funnels for any actions we perform during the deadline.
+  request_swap_funnel_ = false;
 }
 
 void SchedulerStateMachine::OnBeginImplFrameIdle() {
-  DCHECK_EQ(begin_impl_frame_state_, BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
-      << AsValue()->ToString();
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_IDLE;
 }
 
 SchedulerStateMachine::BeginImplFrameDeadlineMode
 SchedulerStateMachine::CurrentBeginImplFrameDeadlineMode() const {
-  if (ShouldTriggerBeginImplFrameDeadlineImmediately()) {
+  if (settings_.using_synchronous_renderer_compositor) {
+    // No deadline for synchronous compositor.
+    return BEGIN_IMPL_FRAME_DEADLINE_MODE_NONE;
+  } else if (ShouldTriggerBeginImplFrameDeadlineImmediately()) {
     return BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE;
   } else if (needs_redraw_ && pending_swaps_ < max_pending_swaps_) {
     // We have an animation or fast input path on the impl thread that wants
     // to draw, so don't wait too long for a new active tree.
     // If we are swap throttled we should wait until we are unblocked.
     return BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR;
   } else {
     // The impl thread doesn't have anything it wants to draw and we are just
     // waiting for a new active tree or we are swap throttled. In short we are
     // blocked.
     return BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE;
   }
 }
 
 bool SchedulerStateMachine::ShouldTriggerBeginImplFrameDeadlineImmediately()
     const {
   // TODO(brianderson): This should take into account multiple commit sources.
-
   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
     return false;
 
   // If we've lost the output surface, end the current BeginImplFrame ASAP
   // so we can start creating the next output surface.
   if (output_surface_state_ == OUTPUT_SURFACE_LOST)
     return true;
 
   // SwapAck throttle the deadline since we wont draw and swap anyway.
   if (pending_swaps_ >= max_pending_swaps_)
@@ skipping 45 matching lines @@
   // or
   //   we're currently drawing the active tree and the pending tree will thus
   //   only be drawn in the next frame.
   if (has_pending_tree_)
     return true;
 
   if (begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE) {
     // Even if there's a new active tree to draw at the deadline or we've just
     // swapped it, it may have been triggered by a previous BeginImplFrame, in
     // which case the main thread is in a high latency mode.
-    return (active_tree_needs_first_draw_ || perform_swap_funnel_) &&
+    return (active_tree_needs_first_draw_ || did_perform_swap_in_last_draw_) &&
            !send_begin_main_frame_funnel_;
   }
 
   // If the active tree needs its first draw in any other state, we know the
   // main thread is in a high latency mode.
   return active_tree_needs_first_draw_;
 }
 
-void SchedulerStateMachine::DidEnterPollForAnticipatedDrawTriggers() {
-  AdvanceCurrentFrameNumber();
-  inside_poll_for_anticipated_draw_triggers_ = true;
-}
-
-void SchedulerStateMachine::DidLeavePollForAnticipatedDrawTriggers() {
-  inside_poll_for_anticipated_draw_triggers_ = false;
-}
-
 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::SetNeedsAnimate() {
   needs_animate_ = true;
 }
 
 void SchedulerStateMachine::SetNeedsPrepareTiles() {
   if (!needs_prepare_tiles_) {
     TRACE_EVENT0("cc", "SchedulerStateMachine::SetNeedsPrepareTiles");
     needs_prepare_tiles_ = true;
   }
 }
 
 void SchedulerStateMachine::SetMaxSwapsPending(int max) {
   max_pending_swaps_ = max;
 }
 
 void SchedulerStateMachine::DidSwapBuffers() {
   pending_swaps_++;
   DCHECK_LE(pending_swaps_, max_pending_swaps_);
-  DCHECK(!perform_swap_funnel_);
 
-  perform_swap_funnel_ = true;
+  did_perform_swap_in_last_draw_ = true;
   last_frame_number_swap_performed_ = current_frame_number_;
 }
 
 void SchedulerStateMachine::DidSwapBuffersComplete() {
   DCHECK_GT(pending_swaps_, 0);
   pending_swaps_--;
 }
 
 void SchedulerStateMachine::SetImplLatencyTakesPriority(
     bool impl_latency_takes_priority) {
@@ skipping 133 matching lines @@
       static_cast<int>(begin_impl_frame_state_),
       static_cast<int>(commit_state_),
       has_pending_tree_ ? 'T' : 'F',
       pending_tree_is_ready_for_activation_ ? 'T' : 'F',
       active_tree_needs_first_draw_ ? 'T' : 'F',
       max_pending_swaps_,
       pending_swaps_);
 }
 
 }  // namespace cc