Revert of cc: Remove tile rasterize on demand for GPU rasterization

cc/resources/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/resources/tile_manager.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 
@@ skipping 400 matching lines @@
 
   // We must reduce the amount of unused resources before calling
   // RunTasks to prevent usage from rising above limits.
   resource_pool_->ReduceResourceUsage();
 
   // Run and complete all raster task synchronously.
   rasterizer_->RasterizeTiles(
       tiles_that_need_to_be_rasterized, resource_pool_,
       base::Bind(&TileManager::UpdateTileDrawInfo, base::Unretained(this)));
 
+  // Use on-demand raster for any required-for-activation tiles that have not
+  // been been assigned memory after reaching a steady memory state. This
+  // ensures that we activate even when OOM. Note that we have to rebuilt the
+  // queue in case the last AssignGpuMemoryToTiles evicted some tiles that would
+  // otherwise not be picked up by the old raster queue.
+  client_->BuildRasterQueue(&raster_priority_queue_,
+                            global_state_.tree_priority);
+
+  // Use on-demand raster for any tiles that have not been been assigned
+  // memory. This ensures that we draw even when OOM.
+  while (!raster_priority_queue_.IsEmpty()) {
+    Tile* tile = raster_priority_queue_.Top();
+    TileDrawInfo& draw_info = tile->draw_info();
+
+    if (tile->required_for_draw() && !draw_info.IsReadyToDraw()) {
+      draw_info.set_rasterize_on_demand();
+      client_->NotifyTileStateChanged(tile);
+    }
+    raster_priority_queue_.Pop();
+  }
+  raster_priority_queue_.Reset();
+
   TRACE_EVENT_INSTANT1("cc", "DidRasterize", TRACE_EVENT_SCOPE_THREAD, "state",
                        BasicStateAsValue());
 
   TRACE_COUNTER_ID1("cc", "unused_memory_bytes", this,
                     resource_pool_->total_memory_usage_bytes() -
                         resource_pool_->acquired_memory_usage_bytes());
 }
 
 void TileManager::UpdateVisibleTiles(
     const GlobalStateThatImpactsTilePriority& state) {
@@ skipping 597 matching lines @@
   result -= other;
   return result;
 }
 
 bool TileManager::MemoryUsage::Exceeds(const MemoryUsage& limit) const {
   return memory_bytes_ > limit.memory_bytes_ ||
          resource_count_ > limit.resource_count_;
 }
 
 }  // namespace cc