Revert of Hook up the Push API with GCM's new ability to own encryption keys.

components/gcm_driver/crypto/gcm_key_store.h

Index: components/gcm_driver/crypto/gcm_key_store.h
diff --git a/components/gcm_driver/crypto/gcm_key_store.h b/components/gcm_driver/crypto/gcm_key_store.h
index d224d5cb4fd99c9c7a9de4fba02fc4fbd01091e2..c35bb310f4bb8e8e93a909fab12460658f40b24b 100644
--- a/components/gcm_driver/crypto/gcm_key_store.h
+++ b/components/gcm_driver/crypto/gcm_key_store.h
@@ -36,9 +36,8 @@
   using KeysCallback = base::Callback<void(const KeyPair& pair)>;
   using DeleteCallback = base::Callback<void(bool success)>;
 
-  GCMKeyStore(
-      const base::FilePath& key_store_path,
-      const scoped_refptr<base::SequencedTaskRunner>& blocking_task_runner);
+  GCMKeyStore(const base::FilePath& key_store_path,
+              scoped_refptr<base::SequencedTaskRunner> background_task_runner);
 
   // Retrieves the public/private key-pair associated with |app_id|, and
   // invokes |callback| when they are available, or when an error occurred.
@@ -86,9 +85,6 @@
   // Path in which the key store database will be saved.
   base::FilePath key_store_path_;
 
-  // Blocking task runner which the database will do I/O operations on.
-  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
-
   // Instance of the ProtoDatabase backing the key store.
   scoped_ptr<leveldb_proto::ProtoDatabase<EncryptionData>> database_;