Update from https://crrev.com/320931

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 130 matching lines @@
 
   // Overridden from Task:
   void RunOnWorkerThread() override {
     TRACE_EVENT0("cc", "ImageDecodeTaskImpl::RunOnWorkerThread");
 
     devtools_instrumentation::ScopedImageDecodeTask image_decode_task(
         pixel_ref_.get());
     // This will cause the image referred to by pixel ref to be decoded.
     pixel_ref_->lockPixels();
     pixel_ref_->unlockPixels();
+
+    // Release the reference after decoding image to ensure that it is not
+    // kept alive unless needed.
+    pixel_ref_.clear();
   }
 
   // Overridden from TileTask:
   void ScheduleOnOriginThread(TileTaskClient* client) override {}
   void CompleteOnOriginThread(TileTaskClient* client) override {}
   void RunReplyOnOriginThread() override { reply_.Run(!HasFinishedRunning()); }
 
  protected:
   ~ImageDecodeTaskImpl() override {}
 
@@ skipping 887 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