Add GPU memory usage contents browser test

content/public/common/gpu_memory_stats.cc

 // Copyright (c) 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 "content/public/common/gpu_memory_stats.h"
 
 namespace content {
 
-GPUVideoMemoryUsageStats::GPUVideoMemoryUsageStats() {
+GPUVideoMemoryUsageStats::GPUVideoMemoryUsageStats()
+    : bytes_allocated(0),
+      bytes_allocated_historical_max(0) {
 }
 
 GPUVideoMemoryUsageStats::~GPUVideoMemoryUsageStats() {
 }
 
 GPUVideoMemoryUsageStats::ProcessStats::ProcessStats()
     : video_memory(0),
       has_duplicates(false) {
 }
 
 GPUVideoMemoryUsageStats::ProcessStats::~ProcessStats() {
 }
 
 }  // namespace content