Clear GCM data when the user clears cookies and other site data

components/gcm_driver/fake_gcm_driver.cc

Index: components/gcm_driver/fake_gcm_driver.cc
diff --git a/components/gcm_driver/fake_gcm_driver.cc b/components/gcm_driver/fake_gcm_driver.cc
index 85cc920b43dc0d93d36315f7054fd0101b7a35c7..7ee53c517329e030ed9a27c456b4f45e812b04fd 100644
--- a/components/gcm_driver/fake_gcm_driver.cc
+++ b/components/gcm_driver/fake_gcm_driver.cc
@@ -25,6 +25,9 @@ void FakeGCMDriver::RemoveAppHandler(const std::string& app_id) {
 void FakeGCMDriver::OnSignedIn() {
 }
 
+void FakeGCMDriver::OnSignedOut() {
+}
+
 void FakeGCMDriver::Purge() {
 }