Make chrome/browser/extensions use base::Clock instead of MockTimeProvider

chrome/browser/extensions/test_extension_system.h

Index: chrome/browser/extensions/test_extension_system.h
diff --git a/chrome/browser/extensions/test_extension_system.h b/chrome/browser/extensions/test_extension_system.h
index d17ac0268f54a14eabbb9d71369f40e5229d62b3..bb845a96d27f7ecbc3c6bfbd2a58ff71e79e4df1 100644
--- a/chrome/browser/extensions/test_extension_system.h
+++ b/chrome/browser/extensions/test_extension_system.h
@@ -10,6 +10,7 @@
 class CommandLine;
 
 namespace base {
+class Clock;
 class FilePath;
 class Time;
 }
@@ -36,7 +37,7 @@ class TestExtensionSystem : public ExtensionSystem {
   void CreateExtensionProcessManager();
 
   // Creates an AlarmManager. Will be NULL otherwise.
-  void CreateAlarmManager(base::Time (*now)());
+  void CreateAlarmManager(base::Clock* clock);
 
   void CreateSocketManager();