components: Cleanup class/struct fwd declarations

components/gcm_driver/gcm_profile_service.h

Index: components/gcm_driver/gcm_profile_service.h
diff --git a/components/gcm_driver/gcm_profile_service.h b/components/gcm_driver/gcm_profile_service.h
index 9094a08d13761ab9961e983a4d1e6a2ef5282f53..b3305b63ad2240e219f751fa7a92e8d5c7c1f909 100644
--- a/components/gcm_driver/gcm_profile_service.h
+++ b/components/gcm_driver/gcm_profile_service.h
@@ -19,8 +19,6 @@
 #include "components/version_info/version_info.h"
 
 class PrefService;
-class ProfileOAuth2TokenService;
-class SigninManagerBase;
 
 namespace base {
 class SequencedTaskRunner;
@@ -30,19 +28,11 @@ namespace net {
 class URLRequestContextGetter;
 }
 
-namespace user_prefs {
-class PrefRegistrySyncable;
-}
-
 namespace gcm {
 
 class GCMClientFactory;
 class GCMDriver;
 
-#if defined(OS_CHROMEOS)
-class GCMConnectionObserver;
-#endif
-
 // Providing GCM service, via GCMDriver.
 class GCMProfileService : public KeyedService {
  public: