Add UMA stats for GPU feature disable checkbox.

chrome/browser/gpu/gpu_mode_manager.cc

Index: chrome/browser/gpu/gpu_mode_manager.cc
===================================================================
--- chrome/browser/gpu/gpu_mode_manager.cc	(revision 193279)
+++ chrome/browser/gpu/gpu_mode_manager.cc	(working copy)
@@ -5,16 +5,38 @@
 #include "chrome/browser/gpu/gpu_mode_manager.h"
 
 #include "base/bind.h"
+#include "base/metrics/histogram.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/gpu_data_manager.h"
+#include "content/public/browser/user_metrics.h"
 
+using content::UserMetricsAction;
+
+namespace {
+
+bool GetPreviousGpuModePref() {
+  PrefService* service = g_browser_process->local_state();
+  DCHECK(service);
+  return service->GetBoolean(prefs::kHardwareAccelerationModePrevious);
+}
+
+void SetPreviousGpuModePref(bool enabled) {
+  PrefService* service = g_browser_process->local_state();
+  DCHECK(service);
+  service->SetBoolean(prefs::kHardwareAccelerationModePrevious, enabled);
+}
+
+}  // namespace anonymous
+
 // static
 void GpuModeManager::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterBooleanPref(
       prefs::kHardwareAccelerationModeEnabled, true);
+  registry->RegisterBooleanPref(
+      prefs::kHardwareAccelerationModePrevious, true);
 }
 
 GpuModeManager::GpuModeManager()
@@ -28,7 +50,16 @@
         base::Bind(&base::DoNothing));
 
     initial_gpu_mode_pref_ = IsGpuModePrefEnabled();
+    bool previous_gpu_mode_pref = GetPreviousGpuModePref();
+    SetPreviousGpuModePref(initial_gpu_mode_pref_);
 
+    UMA_HISTOGRAM_BOOLEAN("GPU.HardwareAccelerationModeEnabled",
+                          initial_gpu_mode_pref_);
+    if (previous_gpu_mode_pref && !initial_gpu_mode_pref_)
+      content::RecordAction(UserMetricsAction("GpuAccelerationDisabled"));
+    if (!previous_gpu_mode_pref && initial_gpu_mode_pref_)
+      content::RecordAction(UserMetricsAction("GpuAccelerationEnabled"));
+
     if (!initial_gpu_mode_pref_) {
       content::GpuDataManager* gpu_data_manager =
           content::GpuDataManager::GetInstance();