cc: Simplify the logic for deciding to update tile priorities.

cc/layers/picture_layer_impl.cc

 // Copyright 2012 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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 
 #include "base/time.h"
 #include "cc/base/math_util.h"
@@ skipping 243 matching lines @@
 }
 
 void PictureLayerImpl::DumpLayerProperties(std::string*, int indent) const {
   // TODO(enne): implement me
 }
 
 void PictureLayerImpl::UpdateTilePriorities() {
   if (!tilings_->num_tilings())
     return;
 
+  double current_frame_time_in_seconds =
+      (layer_tree_impl()->CurrentFrameTimeTicks() -
+       base::TimeTicks()).InSecondsF();
+
+  bool tiling_needs_update = false;
+  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
+    if (tilings_->tiling_at(i)->NeedsUpdateForFrameAtTime(
+            current_frame_time_in_seconds)) {
+      tiling_needs_update = true;
+      break;
+    }
+  }
+  if (!tiling_needs_update)
+    return;
+
   UpdateLCDTextStatus();
 
-  int current_source_frame_number = layer_tree_impl()->source_frame_number();
-  double current_frame_time = (layer_tree_impl()->CurrentFrameTimeTicks() -
-                               base::TimeTicks()).InSecondsF();
-
   gfx::Transform current_screen_space_transform = screen_space_transform();
 
   gfx::Rect viewport_in_content_space;
   gfx::Transform screen_to_layer(gfx::Transform::kSkipInitialization);
   if (screen_space_transform().GetInverse(&screen_to_layer)) {
     gfx::Rect device_viewport(layer_tree_impl()->device_viewport_size());
     viewport_in_content_space = gfx::ToEnclosingRect(
         MathUtil::ProjectClippedRect(screen_to_layer, device_viewport));
   }
 
   WhichTree tree =
       layer_tree_impl()->IsActiveTree() ? ACTIVE_TREE : PENDING_TREE;
   bool store_screen_space_quads_on_tiles =
       layer_tree_impl()->debug_state().trace_all_rendered_frames;
   size_t max_tiles_for_interest_area =
       layer_tree_impl()->settings().max_tiles_for_interest_area;
   tilings_->UpdateTilePriorities(
       tree,
       layer_tree_impl()->device_viewport_size(),
       viewport_in_content_space,
       visible_content_rect(),
       last_bounds_,
       bounds(),
       last_content_scale_,
       contents_scale_x(),
       last_screen_space_transform_,
       current_screen_space_transform,
-      current_source_frame_number,
-      current_frame_time,
+      current_frame_time_in_seconds,
       store_screen_space_quads_on_tiles,
       max_tiles_for_interest_area);
 
   last_screen_space_transform_ = current_screen_space_transform;
   last_bounds_ = bounds();
   last_content_scale_ = contents_scale_x();
 }
 
 void PictureLayerImpl::DidBecomeActive() {
   LayerImpl::DidBecomeActive();
@@ skipping 592 matching lines @@
 scoped_ptr<base::Value> PictureLayerImpl::AsValue() const {
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   LayerImpl::AsValueInto(state.get());
 
   state->SetDouble("ideal_contents_scale", ideal_contents_scale_);
   state->Set("tilings", tilings_->AsValue().release());
   return state.PassAs<base::Value>();
 }
 
 }  // namespace cc