cc: Add a tile manager check to try and diagnose renderer hangs.

cc/tiles/tile_manager.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/tiles/tile_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1053 matching lines @@
 bool TileManager::AreRequiredTilesReadyToDraw(
     RasterTilePriorityQueue::Type type) const {
   std::unique_ptr<RasterTilePriorityQueue> raster_priority_queue(
       client_->BuildRasterQueue(global_state_.tree_priority, type));
   // It is insufficient to check whether the raster queue we constructed is
   // empty. The reason for this is that there are situations (rasterize on
   // demand) when the tile both needs raster and it's ready to draw. Hence, we
   // have to iterate the queue to check whether the required tiles are ready to
   // draw.
   for (; !raster_priority_queue->IsEmpty(); raster_priority_queue->Pop()) {
-    if (!raster_priority_queue->Top().tile()->draw_info().IsReadyToDraw())
+    const auto& prioritized_tile = raster_priority_queue->Top();
+    // TODO(vmpstr): Check to debug crbug.com/622080. Remove when fixed.

[sunnyps, 2016/12/10 01:29:47]

Shouldn't we do this check only for the required for activation queue?

+    CHECK_EQ(prioritized_tile.priority().priority_bin, TilePriority::NOW);
+    if (!prioritized_tile.tile()->draw_info().IsReadyToDraw())
       return false;
   }
 
 #if DCHECK_IS_ON()
   std::unique_ptr<RasterTilePriorityQueue> all_queue(
       client_->BuildRasterQueue(global_state_.tree_priority, type));
   for (; !all_queue->IsEmpty(); all_queue->Pop()) {
     Tile* tile = all_queue->Top().tile();
     DCHECK(!tile->required_for_activation() ||
            tile->draw_info().IsReadyToDraw());
@@ skipping 256 matching lines @@
   all_tile_tasks_completed = false;
   did_notify_all_tile_tasks_completed = false;
 }
 
 TileManager::PrioritizedWorkToSchedule::PrioritizedWorkToSchedule() = default;
 TileManager::PrioritizedWorkToSchedule::PrioritizedWorkToSchedule(
     PrioritizedWorkToSchedule&& other) = default;
 TileManager::PrioritizedWorkToSchedule::~PrioritizedWorkToSchedule() = default;
 
 }  // namespace cc