chromeos: power: Refactor RendererFreezer and add tests

chrome/browser/chromeos/power/renderer_freezer.h

Index: chrome/browser/chromeos/power/renderer_freezer.h
diff --git a/chrome/browser/chromeos/power/renderer_freezer.h b/chrome/browser/chromeos/power/renderer_freezer.h
index 5af26f8cb22a68f0426bfc63910065030b5a6dd1..6a5da1a1c24780b9d6bcf9ee99b8e718a16544e3 100644
--- a/chrome/browser/chromeos/power/renderer_freezer.h
+++ b/chrome/browser/chromeos/power/renderer_freezer.h
@@ -6,7 +6,7 @@
 #define CHROME_BROWSER_CHROMEOS_POWER_RENDERER_FREEZER_H_
 
 #include "base/callback.h"
-#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "chromeos/chromeos_export.h"
@@ -20,7 +20,23 @@ namespace chromeos {
 // destruction.
 class CHROMEOS_EXPORT RendererFreezer : public PowerManagerClient::Observer {
  public:
-  RendererFreezer();
+  class Delegate {
+   public:
+    virtual ~Delegate() {}
+
+    // Freezes the chrome renderers.  Returns true if the operation was
+    // successful.
+    virtual bool FreezeRenderers() = 0;
+
+    // Thaws the chrome renderers.  Returns true if the operation was
+    // successful.
+    virtual bool ThawRenderers() = 0;
+
+    // Returns true iff the delegate is capable of freezing renderers.
+    virtual bool CanFreezeRenderers() = 0;
+  };
+
+  explicit RendererFreezer(scoped_ptr<Delegate> delegate);
   virtual ~RendererFreezer();
 
   // PowerManagerClient::Observer implementation
@@ -28,12 +44,13 @@ class CHROMEOS_EXPORT RendererFreezer : public PowerManagerClient::Observer {
   virtual void SuspendDone(const base::TimeDelta& sleep_duration) OVERRIDE;
 
  private:
+  // Called when all asynchronous work is complete and renderers can be frozen.
   void OnReadyToSuspend();
 
-  base::FilePath state_path_;
-  bool enabled_;
   bool frozen_;
 
+  scoped_ptr<Delegate> delegate_;
+
   // Callback used to asynchronously report suspend readiness.
   base::Closure suspend_readiness_callback_;