CL for perf tryjob on linux

cc/playback/largest_display_item.cc

 // Copyright 2015 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/playback/largest_display_item.h"
 
 #include <algorithm>
 
 #include "cc/playback/clip_display_item.h"
 #include "cc/playback/clip_path_display_item.h"
@@ skipping 50 matching lines @@
   static_assert(sizeof(TransformDisplayItem) <= kLargestDisplayItemSize,
                 "Largest Draw Quad size needs update. TransformDisplayItem"
                 " is currently largest.");
   static_assert(sizeof(EndTransformDisplayItem) <= kLargestDisplayItemSize,
                 "Largest Draw Quad size needs update. EndTransformDisplayItem"
                 " is currently largest.");
 
   return kLargestDisplayItemSize;
 }
 
+size_t TypicalDisplayItemSize() {
+  // We expect most DisplayItems in a large page to be DrawingDisplayItem.
+  return sizeof(DrawingDisplayItem);
+}
+
 }  // namespace cc