[tracing] Implement composable memory usage estimators.

ui/android/resources/resource_manager.cc

 // Copyright 2014 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 "ui/android/resources/resource_manager.h"
 
+#include "base/trace_event/memory_usage_estimator.h"
 #include "ui/gfx/geometry/insets_f.h"
 
 namespace ui {
 
 ResourceManager::Resource::Resource() {
 }
 
 ResourceManager::Resource::~Resource() {
 }
 
@@ skipping 11 matching lines @@
   float left_scale = std::min(x_scale * scale.left(), 1.f);
   float right_scale = std::min(x_scale * scale.right(), 1.f);
   float top_scale = std::min(y_scale * scale.top(), 1.f);
   float bottom_scale = std::min(y_scale * scale.bottom(), 1.f);
 
   return gfx::Rect(aperture.x() * left_scale, aperture.y() * top_scale,
                    (size.width() - aperture.width()) * right_scale,
                    (size.height() - aperture.height()) * bottom_scale);
 }
 
+size_t ResourceManager::Resource::EstimateMemoryUsage() const {
+  return base::trace_event::EstimateMemoryUsage(ui_resource);
+}
+
 }  // namespace ui