Update from https://crrev.com/314320

cc/resources/tile_task_worker_pool.cc

 // Copyright 2013 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_task_worker_pool.h"
 
 #include <algorithm>
 
 #include "base/lazy_instance.h"
 #include "base/strings/stringprintf.h"
@@ skipping 75 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(TaskSetFinishedTaskImpl);
 };
 
 }  // namespace
 
 // This allows a micro benchmark system to run tasks with highest priority,
 // since it should finish as quickly as possible.
 unsigned TileTaskWorkerPool::kBenchmarkTaskPriority = 0u;
 // Task priorities that make sure task set finished tasks run before any
-// other remaining tasks.
-unsigned TileTaskWorkerPool::kTaskSetFinishedTaskPriority = 1u;
-unsigned TileTaskWorkerPool::kTileTaskPriorityBase = 2u;
+// other remaining tasks. This is combined with the task set type to ensure
+// proper prioritization ordering between task set types.
+unsigned TileTaskWorkerPool::kTaskSetFinishedTaskPriorityBase = 1u;
+// For correctness, |kTileTaskPriorityBase| must be greater than
+// |kTaskSetFinishedTaskPriorityBase + kNumberOfTaskSets|.
+unsigned TileTaskWorkerPool::kTileTaskPriorityBase = 10u;
 
 TileTaskWorkerPool::TileTaskWorkerPool() {
 }
 
 TileTaskWorkerPool::~TileTaskWorkerPool() {
 }
 
 // static
 void TileTaskWorkerPool::SetNumWorkerThreads(int num_threads) {
   DCHECK_LT(0, num_threads);
@@ skipping 151 matching lines @@
   // TODO(kaanb): The GL pipeline assumes a 4-byte alignment for the
   // bitmap data. There will be no need to call SkAlign4 once crbug.com/293728
   // is fixed.
   const size_t dst_row_bytes = SkAlign4(dst_info.minRowBytes());
   DCHECK_EQ(0u, dst_row_bytes % 4);
   bool success = canvas->readPixels(dst_info, memory, dst_row_bytes, 0, 0);
   DCHECK_EQ(true, success);
 }
 
 }  // namespace cc