Generate Instance ID locally.

components/gcm_driver/instance_id/instance_id.h

 // 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_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_H_
 #define COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_H_
 
 #include <map>
 #include <string>
 
@@ skipping 27 matching lines @@
   typedef base::Callback<void(InstanceID* instance_id,
                               bool update_id)> TokenRefreshCallback;
   typedef base::Callback<void(InstanceID* instance_id,
                               const std::string& token,
                               Result result)> GetTokenCallback;
   typedef base::Callback<void(InstanceID* instance_id,
                               Result result)> DeleteTokenCallback;
   typedef base::Callback<void(InstanceID* instance_id,
                               Result result)> DeleteIDCallback;
 
+  static const int kInstanceIDByteLength = 8;
+
   // Creator.
   // |app_id|: identifies the application that uses the Instance ID.
   // |callback|: to be called when the token refresh is needed.
   static InstanceID* Create(const std::string& app_id);
 
   virtual ~InstanceID();
 
   // Sets the callback that will be invoked when the token refresh event needs
   // to be triggered.
   void SetTokenRefreshCallback(const TokenRefreshCallback& callback);
@@ skipping 43 matching lines @@
  private:
   std::string app_id_;
   TokenRefreshCallback token_refresh_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(InstanceID);
 };
 
 }  // namespace instance_id
 
 #endif  // COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_H_