[GCM] Remove GCMDriver::Purge and GCMClient::CheckOut

components/gcm_driver/gcm_driver.h

Index: components/gcm_driver/gcm_driver.h
diff --git a/components/gcm_driver/gcm_driver.h b/components/gcm_driver/gcm_driver.h
index a0f38dcc7d57bf8e02b89b3baef8493c7cfd51d0..8d2b0d87a137078ccf612331c71dfe4d9db01b10 100644
--- a/components/gcm_driver/gcm_driver.h
+++ b/components/gcm_driver/gcm_driver.h
@@ -74,10 +74,6 @@ class GCMDriver {
   virtual void OnSignedIn() = 0;
   virtual void OnSignedOut() = 0;
 
-  // Removes all the cached and persisted GCM data. If the GCM service is
-  // restarted after the purge, a new Android ID will be obtained.
-  virtual void Purge() = 0;
-
   // Adds a handler for a given app.
   virtual void AddAppHandler(const std::string& app_id, GCMAppHandler* handler);