cc: Fix impl-side painting flashing due to missing tiles

cc/resources/picture_layer_tiling.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/resources/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/debug/trace_event.h"
@@ skipping 61 matching lines @@
   TileMap::const_iterator iter = tiles_.find(TileMapKey(i, j));
   if (iter == tiles_.end())
     return NULL;
   return iter->second.get();
 }
 
 void PictureLayerTiling::CreateTile(int i, int j) {
   TileMapKey key(i, j);
   DCHECK(tiles_.find(key) == tiles_.end());
 
-  gfx::Rect paint_rect = tiling_data_.TileBoundsWithBorder(i, j);
-  gfx::Rect tile_rect = paint_rect;
+  gfx::Rect tile_rect = tiling_data_.TileBoundsWithBorder(i, j);
   tile_rect.set_size(tiling_data_.max_texture_size());
 
   // Check our twin for a valid tile.
   const PictureLayerTiling* twin = client_->GetTwinTiling(this);
   if (twin && tiling_data_.max_texture_size() ==
       twin->tiling_data_.max_texture_size()) {
     Tile* candidate_tile = twin->TileAt(i, j);
     if (candidate_tile) {
       gfx::Rect rect =
-          gfx::ToEnclosingRect(ScaleRect(paint_rect, 1.0f / contents_scale_));
+          gfx::ToEnclosingRect(ScaleRect(tile_rect, 1.0f / contents_scale_));
       if (!client_->GetInvalidation()->Intersects(rect)) {
         tiles_[key] = candidate_tile;
         return;
       }
     }
   }
 
   // Create a new tile because our twin didn't have a valid one.
   scoped_refptr<Tile> tile = client_->CreateTile(this, tile_rect);
   if (tile)
@@ skipping 184 matching lines @@
     const gfx::RectF& visible_layer_rect,
     gfx::Size last_layer_bounds,
     gfx::Size current_layer_bounds,
     float last_layer_contents_scale,
     float current_layer_contents_scale,
     const gfx::Transform& last_screen_transform,
     const gfx::Transform& current_screen_transform,
     double current_frame_time_in_seconds,
     bool store_screen_space_quads_on_tiles,
     size_t max_tiles_for_interest_area) {
-  if (ContentRect().IsEmpty())
+  if (!NeedsUpdateForFrameAtTime(current_frame_time_in_seconds)) {
+    // This should never be zero for the purposes of has_ever_been_updated().
+    DCHECK_NE(current_frame_time_in_seconds, 0.0);
     return;
-  if (!NeedsUpdateForFrameAtTime(current_frame_time_in_seconds))
+  }
+  if (ContentRect().IsEmpty()) {
+    last_impl_frame_time_in_seconds_ = current_frame_time_in_seconds;
     return;
+  }
 
   gfx::Rect viewport_in_content_space =
       gfx::ToEnclosingRect(gfx::ScaleRect(viewport_in_layer_space,
                                           contents_scale_));
   gfx::Rect visible_content_rect =
       gfx::ToEnclosingRect(gfx::ScaleRect(visible_layer_rect,
                                           contents_scale_));
 
   gfx::Size tile_size = tiling_data_.max_texture_size();
   int64 interest_rect_area =
@@ skipping 290 matching lines @@
 
     // If our delta is less then our event distance, we're done.
     if (delta < event.distance)
       break;
   }
 
   return gfx::Rect(origin_x, origin_y, width, height);
 }
 
 }  // namespace cc