Add calls to inform gpu of browser window count

chrome/browser/chrome_gpu_util.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 "chrome/browser/chrome_gpu_util.h"
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/version.h"
 #if defined(OS_WIN)
 #include "base/win/windows_version.h"
 #endif
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_list.h"
+#include "chrome/browser/ui/browser_list_observer.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
 #include "content/public/browser/gpu_data_manager.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/common/content_switches.h"
 
 using content::GpuDataManager;
 
 namespace gpu_util {
 
+// The BrowserMonitor class is used to track the number of currently open
+// browser windows, so that the gpu can be notified when they are created or
+// destroyed. We only count tabbed windows for this purpose.
+class BrowserMonitor : public chrome::BrowserListObserver {
+ public:
+  static BrowserMonitor* GetInstance() {
+    static BrowserMonitor* instance = NULL;
+    if (!instance)
+      instance = new BrowserMonitor;
+    return instance;
+  }
+
+  void Install() {
+    if (!installed_) {
+      BrowserList::AddObserver(this);
+      installed_ = true;
+    }
+  }
+
+  void Uninstall() {
+    if (installed_) {
+      BrowserList::RemoveObserver(this);
+      installed_ = false;
+    }
+  }
+
+ private:
+  BrowserMonitor() : num_browsers_(0), installed_(false) {
+  }
+
+  ~BrowserMonitor() {
+  }
+
+  // BrowserListObserver implementation.
+  virtual void OnBrowserAdded(Browser* browser) OVERRIDE {
+    if (browser->type() == Browser::TYPE_TABBED)
+      content::GpuDataManager::GetInstance()->SetWindowCount(++num_browsers_);
+  }
+
+  virtual void OnBrowserRemoved(Browser* browser) OVERRIDE {
+    if (browser->type() == Browser::TYPE_TABBED)
+      content::GpuDataManager::GetInstance()->SetWindowCount(--num_browsers_);
+  }
+
+  uint32 num_browsers_;
+  bool installed_;
+};
+
 bool ShouldRunStage3DFieldTrial() {
 #if !defined(OS_WIN)
   return false;
 #else
   if (base::win::GetVersion() >= base::win::VERSION_VISTA)
     return false;
   return true;
 #endif
 }
 
@@ skipping 116 matching lines @@
       content::kGpuCompositingFieldTrialThreadEnabledName,
       threaded_compositing_probability);
 
   bool force_compositing = (trial->group() == force_compositing_group);
   bool thread = (trial->group() == thread_group);
   UMA_HISTOGRAM_BOOLEAN("GPU.InForceCompositingModeFieldTrial",
                         force_compositing);
   UMA_HISTOGRAM_BOOLEAN("GPU.InCompositorThreadFieldTrial", thread);
 }
 
+void InstallBrowserMonitor() {
+  BrowserMonitor::GetInstance()->Install();
+}
+
+void UninstallBrowserMonitor() {
+  BrowserMonitor::GetInstance()->Uninstall();
+}
+
 }  // namespace gpu_util;