settings: Add async system salt retrieval logic in DeviceOAuth2TokenServiceFactory

chrome/browser/chromeos/settings/device_oauth2_token_service_factory.h

Index: chrome/browser/chromeos/settings/device_oauth2_token_service_factory.h
diff --git a/chrome/browser/chromeos/settings/device_oauth2_token_service_factory.h b/chrome/browser/chromeos/settings/device_oauth2_token_service_factory.h
index 16bd680ff573ea51f2d7f42dc6cc14e00cee16da..cd68763b7a870a32bef843431df2619e0b561d18 100644
--- a/chrome/browser/chromeos/settings/device_oauth2_token_service_factory.h
+++ b/chrome/browser/chromeos/settings/device_oauth2_token_service_factory.h
@@ -5,8 +5,12 @@
 #ifndef CHROME_BROWSER_CHROMEOS_SETTINGS_DEVICE_OAUTH2_TOKEN_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_CHROMEOS_SETTINGS_DEVICE_OAUTH2_TOKEN_SERVICE_FACTORY_H_
 
+#include <queue>
+#include <string>
+
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
+#include "base/memory/weak_ptr.h"
 
 namespace chromeos {
 
@@ -45,7 +49,28 @@ class DeviceOAuth2TokenServiceFactory {
   DeviceOAuth2TokenServiceFactory();
   ~DeviceOAuth2TokenServiceFactory();
 
+  // Creates the token service asynchronously in the following steps:
+  // 1) Get the system salt from cryptohomed asynchronously
+  // 2) Create CryptohomeTokenEncryptor using the system salt
+  // 3) Create DeviceOAuth2TokenServiceFactory using the token encryptor
+  void CreateTokenService();
+
+  // Continuation of CreateTokenService(). Called when GetSystemSalt() is
+  // complete.
+  void DidGetSystemSalt(const std::string& system_salt);
+
+  // Runs the callback asynchronously. If |token_service_| is ready, the
+  // callback will be simply run via MessageLoop. Otherwise, the callback
+  // will be queued in |pending_callbacks_| and run when |token_service_| is
+  // ready.
+  void RunAsync(const GetCallback& callback);
+
+  // True if the factory is initialized (i.e. system salt retrieval is done
+  // regardless of whether it succeeded or failed).
+  bool initialized_;
   DeviceOAuth2TokenService* token_service_;
+  std::queue<GetCallback> pending_callbacks_;
+  base::WeakPtrFactory<DeviceOAuth2TokenServiceFactory> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceOAuth2TokenServiceFactory);
 };