cc: Use multiple PrepareTiles approaches

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 5881f2a72340802d180d182fdd7faa4b5a014332..33e33c4544e74076b8d0a963b74d619e4e51c317 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -18,7 +18,8 @@ SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& 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),
+      prepare_tiles_approach_(PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY),
+      prepare_tiles_reason_(PREPARE_TILES_NOT_NEEDED),
       commit_count_(0),
       current_frame_number_(0),
       last_frame_number_animate_performed_(-1),
@@ -31,18 +32,20 @@ SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
       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),
+      last_draw_result_(DRAW_SUCCESS),
+      retry_begin_impl_frame_(false),
+      retry_begin_impl_frame_deadline_(false),
       needs_animate_(false),
-      needs_prepare_tiles_(false),
       needs_commit_(false),
       visible_(false),
       can_start_(false),
       can_draw_(false),
       has_pending_tree_(false),
       pending_tree_is_ready_for_activation_(false),
+      requires_high_res_to_draw_(false),
       active_tree_needs_first_draw_(false),
       did_create_and_initialize_first_output_surface_(false),
       impl_latency_takes_priority_(false),
@@ -103,6 +106,8 @@ const char* SchedulerStateMachine::BeginImplFrameDeadlineModeToString(
       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR";
     case BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE:
       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE";
+    case BEGIN_IMPL_FRAME_DEADLINE_MODE_TRY_TO_AVOID_CHECKERBOARD:
+      return "BEGIN_IMPL_FRAME_DEADLINE_MODE_TRY_TO_AVOID_CHECKERBOARD";
     case BEGIN_IMPL_FRAME_DEADLINE_MODE_BLOCKED_ON_READY_TO_DRAW:
       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_BLOCKED_ON_READY_TO_DRAW";
   }
@@ -129,17 +134,31 @@ const char* SchedulerStateMachine::CommitStateToString(CommitState state) {
   return "???";
 }
 
-const char* SchedulerStateMachine::ForcedRedrawOnTimeoutStateToString(
-    ForcedRedrawOnTimeoutState state) {
-  switch (state) {
-    case FORCED_REDRAW_STATE_IDLE:
-      return "FORCED_REDRAW_STATE_IDLE";
-    case FORCED_REDRAW_STATE_WAITING_FOR_COMMIT:
-      return "FORCED_REDRAW_STATE_WAITING_FOR_COMMIT";
-    case FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION:
-      return "FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION";
-    case FORCED_REDRAW_STATE_WAITING_FOR_DRAW:
-      return "FORCED_REDRAW_STATE_WAITING_FOR_DRAW";
+const char* SchedulerStateMachine::PrepareTilesApproachToString(
+    PrepareTilesApproach approach) {
+  switch (approach) {
+    case PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY:
+      return "PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY";
+    case PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK:
+      return "PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK";
+  }
+  NOTREACHED();
+  return "???";
+}
+
+const char* SchedulerStateMachine::PrepareTilesReasonToString(
+    PrepareTilesReason reason) {
+  switch (reason) {
+    case PREPARE_TILES_NOT_NEEDED:
+      return "PREPARE_TILES_NOT_NEEDED";
+    case PREPARE_TILES_REQUESTED:
+      return "PREPARE_TILES_REQUESTED";
+    case PREPARE_TILES_NEEDED_FOR_COMMIT:
+      return "PREPARE_TILES_NEEDED_FOR_COMMIT";
+    case PREPARE_TILES_NEEDED_FOR_ABORTED_DRAW:
+      return "PREPARE_TILES_NEEDED_FOR_ABORTED_DRAW";
+    case PREPARE_TILES_NEEDED_TO_EVICT_TILES:
+      return "PREPARE_TILES_NEEDED_TO_EVICT_TILES";
   }
   NOTREACHED();
   return "???";
@@ -189,10 +208,12 @@ void SchedulerStateMachine::AsValueInto(
   state->SetString("begin_impl_frame_state",
                    BeginImplFrameStateToString(begin_impl_frame_state_));
   state->SetString("commit_state", CommitStateToString(commit_state_));
-  state->SetString("output_surface_state_",
+  state->SetString("prepare_tiles_approach",
+                   PrepareTilesApproachToString(prepare_tiles_approach_));
+  state->SetString("prepare_tiles_reason",
+                   PrepareTilesReasonToString(prepare_tiles_reason_));
+  state->SetString("output_surface_state",
                    OutputSurfaceStateToString(output_surface_state_));
-  state->SetString("forced_redraw_state",
-                   ForcedRedrawOnTimeoutStateToString(forced_redraw_state_));
   state->EndDictionary();
 
   state->BeginDictionary("minor_state");
@@ -213,13 +234,10 @@ void SchedulerStateMachine::AsValueInto(
   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_);
@@ -344,10 +362,6 @@ bool SchedulerStateMachine::ShouldDraw() const {
   if (begin_impl_frame_state_ != BEGIN_IMPL_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)
-    return true;
-
   return needs_redraw_;
 }
 
@@ -445,14 +459,6 @@ bool SchedulerStateMachine::ShouldSendBeginMainFrame() const {
       BeginFrameNeeded())
     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.
-  // TODO(brianderson): Remove this or move it below the
-  // SendingBeginMainFrameMightCauseDeadlock check since  we want to avoid
-  // ever returning true from this method if we might cause deadlock.
-  if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT)
-    return true;
-
   // We shouldn't normally accept commits if there isn't an OutputSurface.
   if (!HasInitializedOutputSurface())
     return false;
@@ -500,18 +506,36 @@ bool SchedulerStateMachine::ShouldCommit() const {
 }
 
 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;
+  // Handle the clear cut cases.
+  switch (prepare_tiles_reason_) {
+    case PREPARE_TILES_NOT_NEEDED:
+      return false;
+    case PREPARE_TILES_NEEDED_FOR_COMMIT:
+    case PREPARE_TILES_NEEDED_FOR_ABORTED_DRAW:
+    case PREPARE_TILES_NEEDED_TO_EVICT_TILES:
+      return true;
+    case PREPARE_TILES_REQUESTED:
+      break;
+  }
 
-  // Limiting to once per-frame is not enough, since we only want to
-  // prepare tiles _after_ draws.
-  if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
-    return false;
+  switch (prepare_tiles_approach_) {
+    case PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK:
+      return begin_impl_frame_state_ ==
+             BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING;
+    case PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY:
+      break;
+  }
+
+  DCHECK_EQ(PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY, prepare_tiles_approach_);
+  DCHECK_EQ(PREPARE_TILES_REQUESTED, prepare_tiles_reason_);
 
-  return needs_prepare_tiles_;
+  // Only PrepareTiles after a draw if we haven't already PreparedTiles this
+  // frame. This takes PrepareTiles out of the critical path, but wil make the
+  // NotifyReadyToDraw and NotifyReadyToActivate signals liars.
+  bool did_not_prepare_tiles_at_end_of_frame =
+      prepare_tiles_funnel_ == 0 &&
+      begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
+  return did_not_prepare_tiles_at_end_of_frame;
 }
 
 bool SchedulerStateMachine::ShouldInvalidateOutputSurface() const {
@@ -527,10 +551,11 @@ bool SchedulerStateMachine::ShouldInvalidateOutputSurface() const {
   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING)
     return false;
 
+  // TODO(brianderson): Figure out what to do with this.
   // TODO(sunnyps): needs_prepare_tiles_ is needed here because PrepareTiles is
   // called only inside the deadline / draw phase. We could remove this if we
   // allowed PrepareTiles to happen in OnBeginImplFrame.
-  return needs_redraw_ || needs_prepare_tiles_;
+  return needs_redraw_ || PrepareTilesPending();
 }
 
 SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
@@ -543,10 +568,12 @@ SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
   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
+    else if (requires_high_res_to_draw_ ||
+             prepare_tiles_approach_ ==
+                 PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY)
       return ACTION_DRAW_AND_SWAP_IF_POSSIBLE;
+    else
+      return ACTION_DRAW_AND_SWAP_FORCED;
   }
   if (ShouldPrepareTiles())
     return ACTION_PREPARE_TILES;
@@ -559,57 +586,91 @@ SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
   return ACTION_NONE;
 }
 
-void SchedulerStateMachine::UpdateState(Action action) {
+void SchedulerStateMachine::WillAction(Action action) {
   switch (action) {
     case ACTION_NONE:
       return;
 
+    case ACTION_COMMIT:
+      WillCommit();
+      return;
+
     case ACTION_ACTIVATE_SYNC_TREE:
-      UpdateStateOnActivation();
+      WillActivateSyncTree();
       return;
 
     case ACTION_ANIMATE:
-      UpdateStateOnAnimate();
+      WillAnimate();
       return;
 
     case ACTION_SEND_BEGIN_MAIN_FRAME:
-      UpdateStateOnSendBeginMainFrame();
+      WillSendBeginMainFrame();
+      return;
+
+    case ACTION_DRAW_AND_SWAP_FORCED:
+    case ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
+    case ACTION_DRAW_AND_SWAP_ABORT:
+      return;
+
+    case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
+      WillBeginOutputSurfaceCreation();
+      return;
+
+    case ACTION_PREPARE_TILES:
+      return;
+
+    case ACTION_INVALIDATE_OUTPUT_SURFACE:
+      WillInvalidateOutputSurface();
+      return;
+  }
+}
+
+void SchedulerStateMachine::DidAction(Action action) {
+  switch (action) {
+    case ACTION_NONE:
       return;
 
     case ACTION_COMMIT: {
       bool commit_has_no_updates = false;
-      UpdateStateOnCommit(commit_has_no_updates);
+      DidCommit(commit_has_no_updates);
       return;
     }
 
+    case ACTION_ACTIVATE_SYNC_TREE:
+      return;
+
+    case ACTION_ANIMATE:
+      return;
+
+    case ACTION_SEND_BEGIN_MAIN_FRAME:
+      return;
+
     case ACTION_DRAW_AND_SWAP_FORCED:
     case ACTION_DRAW_AND_SWAP_IF_POSSIBLE: {
       bool did_request_swap = true;
-      UpdateStateOnDraw(did_request_swap);
+      DidDraw(did_request_swap);
       return;
     }
 
     case ACTION_DRAW_AND_SWAP_ABORT: {
       bool did_request_swap = false;
-      UpdateStateOnDraw(did_request_swap);
+      DidDraw(did_request_swap);
       return;
     }
 
     case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
-      UpdateStateOnBeginOutputSurfaceCreation();
       return;
 
     case ACTION_PREPARE_TILES:
-      UpdateStateOnPrepareTiles();
+      DidPrepareTiles();
       return;
 
     case ACTION_INVALIDATE_OUTPUT_SURFACE:
-      UpdateStateOnInvalidateOutputSurface();
       return;
   }
 }
 
-void SchedulerStateMachine::UpdateStateOnAnimate() {
+void SchedulerStateMachine::WillAnimate() {
   DCHECK(!animate_funnel_);
   last_frame_number_animate_performed_ = current_frame_number_;
   animate_funnel_ = true;
@@ -618,7 +679,7 @@ void SchedulerStateMachine::UpdateStateOnAnimate() {
   SetNeedsRedraw();
 }
 
-void SchedulerStateMachine::UpdateStateOnSendBeginMainFrame() {
+void SchedulerStateMachine::WillSendBeginMainFrame() {
   DCHECK(!has_pending_tree_ || settings_.main_frame_before_activation_enabled);
   DCHECK(visible_);
   DCHECK(!send_begin_main_frame_funnel_);
@@ -628,7 +689,13 @@ void SchedulerStateMachine::UpdateStateOnSendBeginMainFrame() {
   last_frame_number_begin_main_frame_sent_ = current_frame_number_;
 }
 
-void SchedulerStateMachine::UpdateStateOnCommit(bool commit_has_no_updates) {
+void SchedulerStateMachine::WillCommit() {
+  // The commit may set this synchronously if the new pending tree is
+  // ready for activation immediately.
+  pending_tree_is_ready_for_activation_ = false;
+}
+
+void SchedulerStateMachine::DidCommit(bool commit_has_no_updates) {
   commit_count_++;
 
   // Animate after commit even if we've already animated.
@@ -649,13 +716,6 @@ void SchedulerStateMachine::UpdateStateOnCommit(bool commit_has_no_updates) {
   // mostly as if we are not impl-side-painting since there is no pending tree.
   has_pending_tree_ = settings_.impl_side_painting && !commit_has_no_updates;
 
-  // Update state related to forced draws.
-  if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT) {
-    forced_redraw_state_ = has_pending_tree_
-                               ? FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION
-                               : FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
-  }
-
   // Update the output surface state.
   DCHECK_NE(output_surface_state_, OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION);
   if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT) {
@@ -667,24 +727,19 @@ void SchedulerStateMachine::UpdateStateOnCommit(bool commit_has_no_updates) {
     }
   }
 
-  // Update state if we have a new active tree to draw, or if the active tree
-  // was unchanged but we need to do a forced draw.
-  if (!has_pending_tree_ &&
-      (!commit_has_no_updates ||
-       forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)) {
+  // Update state if we have a new active tree to draw.
+  if (!has_pending_tree_) {
     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 (continuous_painting_)
     needs_commit_ = true;
   last_commit_had_no_updates_ = commit_has_no_updates;
 }
 
-void SchedulerStateMachine::UpdateStateOnActivation() {
+void SchedulerStateMachine::WillActivateSyncTree() {
   if (commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION) {
     commit_state_ = settings_.main_thread_should_always_be_low_latency
                         ? COMMIT_STATE_WAITING_FOR_DRAW
@@ -694,19 +749,13 @@ void SchedulerStateMachine::UpdateStateOnActivation() {
   if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION)
     output_surface_state_ = OUTPUT_SURFACE_ACTIVE;
 
-  if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION)
-    forced_redraw_state_ = FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
-
   has_pending_tree_ = false;
   pending_tree_is_ready_for_activation_ = false;
   active_tree_needs_first_draw_ = true;
   needs_redraw_ = true;
 }
 
-void SchedulerStateMachine::UpdateStateOnDraw(bool did_request_swap) {
-  if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
-    forced_redraw_state_ = FORCED_REDRAW_STATE_IDLE;
-
+void SchedulerStateMachine::DidDraw(bool did_request_swap) {
   if (commit_state_ == COMMIT_STATE_WAITING_FOR_DRAW)
     commit_state_ = COMMIT_STATE_IDLE;
 
@@ -719,13 +768,68 @@ void SchedulerStateMachine::UpdateStateOnDraw(bool did_request_swap) {
     did_request_swap_in_last_frame_ = true;
     last_frame_number_swap_requested_ = current_frame_number_;
   }
+
+  switch (last_draw_result_) {
+    case INVALID_RESULT:
+      NOTREACHED() << "Uninitialized DrawResult.";
+      break;
+
+    case DRAW_ABORTED_CANT_DRAW:
+    case DRAW_ABORTED_CONTEXT_LOST:
+      NOTREACHED() << "Invalid return value from DrawAndSwapIfPossible:"
+                   << last_draw_result_;
+      break;
+
+    case DRAW_SUCCESS:
+      break;
+
+    case DRAW_ABORTED_MISSING_RASTER_OUTPUT_HIGH_RES:
+    case DRAW_ABORTED_MISSING_RASTER_OUTPUT_ANY_RES:
+      prepare_tiles_reason_ = PREPARE_TILES_NEEDED_FOR_ABORTED_DRAW;
+      if (prepare_tiles_approach_ ==
+          PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY) {
+        prepare_tiles_approach_ = PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK;
+      }
+      retry_begin_impl_frame_deadline_ = true;
+      needs_redraw_ = true;
+      break;
+
+    case DRAW_ABORTED_MISSING_RASTER_SOURCE:
+      prepare_tiles_reason_ = PREPARE_TILES_NEEDED_FOR_ABORTED_DRAW;
+      if (prepare_tiles_approach_ ==
+          PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY) {
+        prepare_tiles_approach_ = PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK;
+      }
+
+      if (CommitPending() || has_pending_tree_) {
+        // The new active tree in flight might have an updated raster source,
+        // so wait and see.
+        retry_begin_impl_frame_deadline_ = true;
+      } else {
+        // We need a new active tree to get an updated raster source.
+        needs_commit_ = true;
+        retry_begin_impl_frame_ = true;
+      }
+
+      // This is one of the few cases where we actively avoid drawing a commit.
+      // Skipping draw of the commit can be better than a flash of checkerboard.
+      active_tree_needs_first_draw_ = false;
+      break;
+  }
 }
 
-void SchedulerStateMachine::UpdateStateOnPrepareTiles() {
-  needs_prepare_tiles_ = false;
+void SchedulerStateMachine::DidPrepareTiles() {
+  prepare_tiles_reason_ = PREPARE_TILES_NOT_NEEDED;
+
+  active_tree_ready_to_draw_ = false;
+
+  if (prepare_tiles_approach_ == PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY)
+    prepare_tiles_funnel_++;
+  else
+    prepare_tiles_funnel_ = 0;
 }
 
-void SchedulerStateMachine::UpdateStateOnBeginOutputSurfaceCreation() {
+void SchedulerStateMachine::WillBeginOutputSurfaceCreation() {
   DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_LOST);
   output_surface_state_ = OUTPUT_SURFACE_CREATING;
 
@@ -737,7 +841,7 @@ void SchedulerStateMachine::UpdateStateOnBeginOutputSurfaceCreation() {
   DCHECK(!active_tree_needs_first_draw_);
 }
 
-void SchedulerStateMachine::UpdateStateOnInvalidateOutputSurface() {
+void SchedulerStateMachine::WillInvalidateOutputSurface() {
   DCHECK(!invalidate_output_surface_funnel_);
   invalidate_output_surface_funnel_ = true;
   last_frame_number_invalidate_output_surface_performed_ =
@@ -787,6 +891,13 @@ void SchedulerStateMachine::SetVideoNeedsBeginFrames(
   video_needs_begin_frames_ = video_needs_begin_frames;
 }
 
+void SchedulerStateMachine::NotifyBeginFrameSourceActive(bool active) {
+  // Upon becoming inactive, switch back to prioritizing latency.
+  if (!active &&
+      prepare_tiles_approach_ == PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK)
+    prepare_tiles_approach_ = PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY;
+}
+
 void SchedulerStateMachine::SetDeferCommits(bool defer_commits) {
   defer_commits_ = defer_commits;
 }
@@ -794,11 +905,6 @@ void SchedulerStateMachine::SetDeferCommits(bool defer_commits) {
 // These are the cases where we require a BeginFrame message to make progress
 // on requested actions.
 bool SchedulerStateMachine::BeginFrameRequiredForAction() const {
-  // The forced draw respects our normal draw scheduling, so we need to
-  // request a BeginImplFrame for it.
-  if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
-    return true;
-
   return needs_animate_ || needs_redraw_ || (needs_commit_ && !defer_commits_);
 }
 
@@ -828,7 +934,7 @@ bool SchedulerStateMachine::ProactiveBeginFrameWanted() const {
 
   // Changing priorities may allow us to activate (given the new priorities),
   // which may result in a new frame.
-  if (needs_prepare_tiles_)
+  if (PrepareTilesPending())
     return true;
 
   // If we just sent a swap request, it's likely that we are going to produce
@@ -851,6 +957,9 @@ void SchedulerStateMachine::OnBeginImplFrame() {
   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING;
   current_frame_number_++;
 
+  retry_begin_impl_frame_ = false;
+  retry_begin_impl_frame_deadline_ = false;
+
   last_commit_had_no_updates_ = false;
   did_request_swap_in_last_frame_ = false;
 
@@ -863,6 +972,15 @@ void SchedulerStateMachine::OnBeginImplFrame() {
   if (prepare_tiles_funnel_ > 0)
     prepare_tiles_funnel_--;
 
+  // PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK doesn't work well in
+  // main thread low-latency mode. Transition back to
+  // PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY if we just recovered
+  // main-thread latency.
+  if (skip_begin_main_frame_to_reduce_latency_ &&
+      prepare_tiles_approach_ == PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK) {
+    prepare_tiles_approach_ = PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY;
+  }
+
   skip_begin_main_frame_to_reduce_latency_ =
       skip_next_begin_main_frame_to_reduce_latency_;
   skip_next_begin_main_frame_to_reduce_latency_ = false;
@@ -896,17 +1014,23 @@ SchedulerStateMachine::CurrentBeginImplFrameDeadlineMode() const {
     return BEGIN_IMPL_FRAME_DEADLINE_MODE_BLOCKED_ON_READY_TO_DRAW;
   } 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;
   }
+
+  if (prepare_tiles_approach_ == PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY) {
+    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;
+    }
+  }
+
+  return BEGIN_IMPL_FRAME_DEADLINE_MODE_TRY_TO_AVOID_CHECKERBOARD;
 }
 
 bool SchedulerStateMachine::ShouldTriggerBeginImplFrameDeadlineImmediately()
@@ -923,6 +1047,11 @@ bool SchedulerStateMachine::ShouldTriggerBeginImplFrameDeadlineImmediately()
   if (pending_swaps_ >= max_pending_swaps_)
     return false;
 
+  // PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY is the only approach
+  // where we want to trigger the deadline before NotifyReadyToDraw.
+  if (prepare_tiles_approach_ != PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY)
+    return active_tree_ready_to_draw_;
+
   if (active_tree_needs_first_draw_)
     return true;
 
@@ -985,7 +1114,11 @@ bool SchedulerStateMachine::MainThreadIsInHighLatencyMode() const {
   return active_tree_needs_first_draw_;
 }
 
-void SchedulerStateMachine::SetVisible(bool visible) { visible_ = visible; }
+void SchedulerStateMachine::SetVisible(bool visible) {
+  visible_ = visible;
+  if (!visible)
+    prepare_tiles_reason_ = PREPARE_TILES_NEEDED_TO_EVICT_TILES;
+}
 
 void SchedulerStateMachine::SetCanDraw(bool can_draw) { can_draw_ = can_draw; }
 
@@ -1000,10 +1133,22 @@ void SchedulerStateMachine::SetWaitForReadyToDraw() {
   wait_for_active_tree_ready_to_draw_ = true;
 }
 
-void SchedulerStateMachine::SetNeedsPrepareTiles() {
-  if (!needs_prepare_tiles_) {
-    TRACE_EVENT0("cc", "SchedulerStateMachine::SetNeedsPrepareTiles");
-    needs_prepare_tiles_ = true;
+void SchedulerStateMachine::SetNeedsPrepareTiles(bool for_commit) {
+  TRACE_EVENT0("cc", "SchedulerStateMachine::SetNeedsPrepareTiles");
+  switch (prepare_tiles_approach_) {
+    case PREPARE_TILES_APPROACH_PRIORITIZE_LATENCY:
+      if (for_commit)
+        prepare_tiles_reason_ = PREPARE_TILES_NEEDED_FOR_COMMIT;
+      else if (prepare_tiles_reason_ == PREPARE_TILES_NOT_NEEDED)
+        prepare_tiles_reason_ = PREPARE_TILES_REQUESTED;
+      break;
+
+    case PREPARE_TILES_APPROACH_ACCURATE_ACTIVE_WORK:
+      // We don't uncondititionally PrepareTiles immediately after a commit with
+      // this approach.
+      if (prepare_tiles_reason_ == PREPARE_TILES_NOT_NEEDED)
+        prepare_tiles_reason_ = PREPARE_TILES_REQUESTED;
+      break;
   }
 }
 
@@ -1029,47 +1174,8 @@ void SchedulerStateMachine::SetImplLatencyTakesPriority(
   impl_latency_takes_priority_ = impl_latency_takes_priority;
 }
 
-void SchedulerStateMachine::DidDrawIfPossibleCompleted(DrawResult result) {
-  switch (result) {
-    case INVALID_RESULT:
-      NOTREACHED() << "Uninitialized DrawResult.";
-      break;
-    case DRAW_ABORTED_CANT_DRAW:
-    case DRAW_ABORTED_CONTEXT_LOST:
-      NOTREACHED() << "Invalid return value from DrawAndSwapIfPossible:"
-                   << result;
-      break;
-    case DRAW_SUCCESS:
-      consecutive_checkerboard_animations_ = 0;
-      forced_redraw_state_ = FORCED_REDRAW_STATE_IDLE;
-      break;
-    case DRAW_ABORTED_CHECKERBOARD_ANIMATIONS:
-      needs_redraw_ = true;
-
-      // If we're already in the middle of a redraw, we don't need to
-      // restart it.
-      if (forced_redraw_state_ != FORCED_REDRAW_STATE_IDLE)
-        return;
-
-      needs_commit_ = true;
-      consecutive_checkerboard_animations_++;
-      if (settings_.timeout_and_draw_when_animation_checkerboards &&
-          consecutive_checkerboard_animations_ >=
-              settings_.maximum_number_of_failed_draws_before_draw_is_forced_) {
-        consecutive_checkerboard_animations_ = 0;
-        // We need to force a draw, but it doesn't make sense to do this until
-        // we've committed and have new textures.
-        forced_redraw_state_ = FORCED_REDRAW_STATE_WAITING_FOR_COMMIT;
-      }
-      break;
-    case DRAW_ABORTED_MISSING_HIGH_RES_CONTENT:
-      // It's not clear whether this missing content is because of missing
-      // pictures (which requires a commit) or because of memory pressure
-      // removing textures (which might not).  To be safe, request a commit
-      // anyway.
-      needs_commit_ = true;
-      break;
-  }
+void SchedulerStateMachine::SetDrawResult(DrawResult result) {
+  last_draw_result_ = result;
 }
 
 void SchedulerStateMachine::SetNeedsCommit() {
@@ -1098,17 +1204,11 @@ void SchedulerStateMachine::BeginMainFrameAborted(CommitEarlyOutReason reason) {
       return;
     case CommitEarlyOutReason::FINISHED_NO_UPDATES:
       bool commit_has_no_updates = true;
-      UpdateStateOnCommit(commit_has_no_updates);
+      DidCommit(commit_has_no_updates);
       return;
   }
 }
 
-void SchedulerStateMachine::DidPrepareTiles() {
-  needs_prepare_tiles_ = false;
-  // "Fill" the PrepareTiles funnel.
-  prepare_tiles_funnel_++;
-}
-
 void SchedulerStateMachine::DidLoseOutputSurface() {
   if (output_surface_state_ == OUTPUT_SURFACE_LOST ||
       output_surface_state_ == OUTPUT_SURFACE_CREATING)
@@ -1119,12 +1219,18 @@ void SchedulerStateMachine::DidLoseOutputSurface() {
 }
 
 void SchedulerStateMachine::NotifyReadyToActivate() {
-  if (has_pending_tree_)
-    pending_tree_is_ready_for_activation_ = true;
+  pending_tree_is_ready_for_activation_ = true;
 }
 
 void SchedulerStateMachine::NotifyReadyToDraw() {
   wait_for_active_tree_ready_to_draw_ = false;
+  active_tree_ready_to_draw_ = true;
+}
+
+void SchedulerStateMachine::SetRequiresHighResToDraw(bool required) {
+  if (requires_high_res_to_draw_ == required)
+    return;
+  requires_high_res_to_draw_ = required;
 }
 
 void SchedulerStateMachine::DidCreateAndInitializeOutputSurface() {