Split WarningService from ExtensionSystem.

extensions/browser/extension_system.h

Index: extensions/browser/extension_system.h
diff --git a/extensions/browser/extension_system.h b/extensions/browser/extension_system.h
index c10697e57a5156e4b11081596427bda0c891ed34..07e1225b3bcada6b6be19dd35836e2524a4183d6 100644
--- a/extensions/browser/extension_system.h
+++ b/extensions/browser/extension_system.h
@@ -41,12 +41,10 @@ class InstallVerifier;
 class LazyBackgroundTaskQueue;
 class ManagementPolicy;
 class OneShotEvent;
-class ProcessManager;
 class QuotaService;
 class RuntimeData;
 class SharedUserScriptMaster;
 class StateStore;
-class WarningService;
 
 // ExtensionSystem manages the lifetime of many of the services used by the
 // extensions and apps system, and it handles startup and shutdown as needed.
@@ -95,9 +93,6 @@ class ExtensionSystem : public KeyedService {
   // The EventRouter is created at startup.
   virtual EventRouter* event_router() = 0;
 
-  // The WarningService is created at startup.
-  virtual WarningService* warning_service() = 0;
-
   // The blacklist is created at startup.
   virtual Blacklist* blacklist() = 0;