Add screen power save block level.

content/browser/power_save_blocker.h

 // 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.
 
 #ifndef CONTENT_BROWSER_POWER_SAVE_BLOCKER_H_
 #define CONTENT_BROWSER_POWER_SAVE_BLOCKER_H_
 #pragma once
 
+#include <vector>
+
 #include "base/basictypes.h"
 
 // A RAII-style class to block the system from entering low-power (sleep) mode.
 class PowerSaveBlocker {
  public:
-  explicit PowerSaveBlocker(bool enabled);
+  enum PowerSaveBlockerType {
+    kPowerSaveBlockPreventNone = -1,
+
+    // Prevent the system from going to sleep; allow display sleep.
+    kPowerSaveBlockPreventSystemSleep,
+
+    // Prevent the system or display from going to sleep.
+    kPowerSaveBlockPreventDisplaySleep,
+
+    kPowerSaveBlockPreventStateCount

[Mark Mentovai, 2011/10/13 04:29:18]

Can you make this be a constant that’s not part of the enum? It makes the
interface a little questionable, since the compiler will be happy to accept this
as an argument to the PowerSaveBlocker constructor and to ApplyBlock.

+  };
+
+  explicit PowerSaveBlocker(PowerSaveBlockerType type);
   ~PowerSaveBlocker();
 
-  bool enabled() const { return enabled_; }
-
-  // Puts the sleep mode block into effect.
-  void Enable();
-  // Disables the sleep block.
-  void Disable();
-
  private:
   // Platform-specific function called when enable state is changed.
   // Guaranteed to be called only from the UI thread.
-  static void ApplyBlock(bool blocked);
+  static void ApplyBlock(PowerSaveBlockerType type);
 
   // Called only from UI thread.
-  static void AdjustBlockCount(int delta);
+  static void AdjustBlockCount(std::vector<int> deltas);

[jam, 2011/10/13 16:40:29]

const ref

[Avi (use Gerrit), 2011/10/13 17:52:44]

The reason I didn't was because I have a question. Is PostTask smart enough to
make a copy when crossing threads? Otherwise, passing by const reference is the
same as passing by pointer, and that would be bad.

[jam, 2011/10/13 18:38:35]

yep it makes a copy

 
   // Invokes AdjustBlockCount on the UI thread.
-  static void PostAdjustBlockCount(int delta);
+  static void PostAdjustBlockCount(const std::vector<int>& deltas);
 
-  bool enabled_;
+  // Returns the highest-severity block type in use.
+  static PowerSaveBlockerType HighestBlockType();
 
-  static int blocker_count_;
+  PowerSaveBlockerType type_;
+
+  static int blocker_count_[];
 
   DISALLOW_COPY_AND_ASSIGN(PowerSaveBlocker);
 };
 
 #endif  // CONTENT_BROWSER_POWER_SAVE_BLOCKER_H_