Add screen power save block level.

content/browser/power_save_blocker_win.cc

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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/browser/power_save_blocker.h"
 
 #include <windows.h>
 
 #include "content/browser/browser_thread.h"
 
-// Runs on UI thread only.
-void PowerSaveBlocker::ApplyBlock(bool blocking) {
+// Called only from UI thread.
+// static
+void PowerSaveBlocker::ApplyBlock(PowerSaveBlockerType type) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   DWORD flags = ES_CONTINUOUS;
 
-  if (blocking)
-    flags |= ES_SYSTEM_REQUIRED;
+  switch (type) {
+    case kPowerSaveBlockPreventSystemSleep:
+      flags |= ES_SYSTEM_REQUIRED;
+      break;
+    case kPowerSaveBlockPreventDisplaySleep:
+      flags |= ES_DISPLAY_REQUIRED;
+      break;
+    default:
+      break;
+  }
 
   SetThreadExecutionState(flags);
 }