Introduce CryptAuthGCMManager, which handles GCM interactions for CryptAuth.

components/proximity_auth/cryptauth/cryptauth_gcm_manager.h

Index: components/proximity_auth/cryptauth/cryptauth_gcm_manager.h
diff --git a/components/proximity_auth/cryptauth/cryptauth_gcm_manager.h b/components/proximity_auth/cryptauth/cryptauth_gcm_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..da461d240cdb88590753ae31bc6ee0883ec25e0e
--- /dev/null
+++ b/components/proximity_auth/cryptauth/cryptauth_gcm_manager.h
@@ -0,0 +1,64 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_PROXIMITY_AUTH_CRYPTAUTH_CRYPTAUTH_GCM_MANAGER_H
+#define COMPONENTS_PROXIMITY_AUTH_CRYPTAUTH_CRYPTAUTH_GCM_MANAGER_H
+
+#include <string>
+
+class PrefRegistrySimple;
+
+namespace proximity_auth {
+
+// Interface for the manager controlling GCM registrations and handling GCM push
+// messages for CryptAuth. CryptAuth sends GCM messages to request the local
+// device to re-enroll to get the freshest device state, and to notify the
+// local device to resync the remote device list when this list changes.
+class CryptAuthGCMManager {
+ public:
+  class Observer {
+   public:
+    virtual ~Observer();
+
+    // Called when a gcm registration attempt finishes with the |success| of the
+    // attempt.
+    virtual void OnGCMRegistrationResult(bool success);
+
+    // Called when a GCM message is received to re-enroll the device with
+    // CryptAuth.
+    virtual void OnReenrollMessage();
+
+    // Called when a GCM message is received to sync down new devices from
+    // CryptAuth.
+    virtual void OnResyncMessage();
+  };
+
+  virtual ~CryptAuthGCMManager() {}
+
+  // Registers the prefs used by the manager to the given |pref_service|.
+  static void RegisterPrefs(PrefRegistrySimple* registry);
+
+  // Starts listening to incoming GCM messages. If GCM registration is completed
+  // after this function is called, then messages will also be handled properly.
+  virtual void StartListening() = 0;
+
+  // Begins registration with GCM. The OnRegistrationCompleted() observer
+  // function will be called with registration completes.

[sacomoto, 2015/07/10 10:54:14]

nit: s/with/when/

[sacomoto, 2015/07/10 10:54:14]

This comment is not very clear. Do you mean the |OnRegistrationCompleted()|
callback declared in the implementation?

[Tim Song, 2015/07/10 20:52:03]

Oops, I meant the Observer::OnGCMRegistrationResult() function.

[Tim Song, 2015/07/10 20:52:04]

Done.

+  virtual void RegisterWithGCM() = 0;
+
+  // Returns the GCM registration id received from the last successful
+  // registration. If registration has not been performed, then an empty string
+  // will be returned.
+  virtual std::string GetRegistrationId() = 0;
+
+  // Adds an observer.
+  virtual void AddObserver(Observer* observer) = 0;
+
+  // Removes an observer.
+  virtual void RemoveObserver(Observer* observer) = 0;
+};
+
+}  // namespace proximity_auth
+
+#endif  // COMPONENTS_PROXIMITY_CRYPTAUTH_CRYPTAUTH_GCM_MANAGER_H