Add screen power save block level.

content/browser/power_save_blocker.h

Index: content/browser/power_save_blocker.h
diff --git a/content/browser/power_save_blocker.h b/content/browser/power_save_blocker.h
index 7d04e6ebbdd5f31c8c7ef16a184424e11acd6d6f..48ebbc094db27c58114b9e6bfaa4e1cda2ed8378 100644
--- a/content/browser/power_save_blocker.h
+++ b/content/browser/power_save_blocker.h
@@ -6,35 +6,48 @@
 #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);
-  ~PowerSaveBlocker();
+  enum PowerSaveBlockerType {
+    kPowerSaveBlockPreventNone = -1,
+
+    // Prevent the system from going to sleep; allow display sleep.
+    kPowerSaveBlockPreventSystemSleep,
 
-  bool enabled() const { return enabled_; }
+    // Prevent the system or display from going to sleep.
+    kPowerSaveBlockPreventDisplaySleep,
 
-  // Puts the sleep mode block into effect.
-  void Enable();
-  // Disables the sleep block.
-  void Disable();
+    // Count of the values; not valid as a parameter.
+    kPowerSaveBlockPreventStateCount

[Avi (use Gerrit), 2011/10/14 00:16:06]

The pattern of putting a count as the last item in an enum is as old as time. If
I don't do this, compiles die.

+  };
+
+  // Pass in the level of sleep prevention desired. kPowerSaveBlockPreventNone
+  // is not a valid option.
+  explicit PowerSaveBlocker(PowerSaveBlockerType type);
+  ~PowerSaveBlocker();
 
  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(const std::vector<int>& deltas);
 
   // Invokes AdjustBlockCount on the UI thread.
-  static void PostAdjustBlockCount(int delta);
+  static void PostAdjustBlockCount(const std::vector<int>& deltas);
+
+  // Returns the highest-severity block type in use.
+  static PowerSaveBlockerType HighestBlockType();
 
-  bool enabled_;
+  PowerSaveBlockerType type_;
 
-  static int blocker_count_;
+  static int blocker_count_[];
 
   DISALLOW_COPY_AND_ASSIGN(PowerSaveBlocker);
 };