Refactor AO2TS to make it easier to componentize.

chrome/browser/chromeos/settings/device_oauth2_token_service.h

Index: chrome/browser/chromeos/settings/device_oauth2_token_service.h
diff --git a/chrome/browser/chromeos/settings/device_oauth2_token_service.h b/chrome/browser/chromeos/settings/device_oauth2_token_service.h
index 4941c0279dcdc79bfffde0d230cdb730ad1d42be..1e1735dca8049b4e1cb332aff6899fde4547c563 100644
--- a/chrome/browser/chromeos/settings/device_oauth2_token_service.h
+++ b/chrome/browser/chromeos/settings/device_oauth2_token_service.h
@@ -18,6 +18,7 @@
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #include "google_apis/gaia/gaia_oauth_client.h"
 #include "google_apis/gaia/oauth2_token_service.h"
+#include "google_apis/gaia/oauth2_token_service_delegate.h"
 #include "net/url_request/url_request_context_getter.h"
 
 namespace gaia {
@@ -46,6 +47,30 @@ namespace chromeos {
 class DeviceOAuth2TokenService : public OAuth2TokenService,
                                  public gaia::GaiaOAuthClient::Delegate {
  public:
+  class DeviceOAuth2TokenServiceDelegate : public OAuth2TokenServiceDelegate {

[xiyuan, 2015/06/26 18:15:53]

nit: We can probably move DeviceOAuth2TokenServiceDelegate declartion into cc
file. See https://www.chromium.org/developers/coding-style/cpp-dos-and-donts,
look for "Move inner classes into the implementation."

Also, does this class needs to be public?

+   public:
+    friend class DeviceOAuth2TokenService;

[xiyuan, 2015/06/26 18:15:53]

Do we need this? Think inner class is friend of outer class by default.

+    DeviceOAuth2TokenServiceDelegate(
+        DeviceOAuth2TokenService* device_token_service);
+    ~DeviceOAuth2TokenServiceDelegate() override;
+
+    OAuth2AccessTokenFetcher* CreateAccessTokenFetcher(

[xiyuan, 2015/06/26 18:15:53]

nit: // OAuth2TokenServiceDelegate

+        const std::string& account_id,
+        net::URLRequestContextGetter* getter,
+        OAuth2AccessTokenConsumer* consumer) override;
+
+    bool RefreshTokenIsAvailable(const std::string& account_id) const override;
+    void UpdateAuthError(const std::string& account_id,
+                         const GoogleServiceAuthError& error) override;
+
+    std::vector<std::string> GetAccounts() override;
+    void RevokeAllCredentials() override;
+    net::URLRequestContextGetter* GetRequestContext() const override;
+
+   private:
+    DeviceOAuth2TokenService* device_token_service_;

[xiyuan, 2015/06/26 18:15:53]

nit: DISALLOW_COPY_AND_ASSIGN(...);

+  };
+
   typedef base::Callback<void(bool)> StatusCallback;
 
   // Persist the given refresh token on the device. Overwrites any previous
@@ -56,9 +81,6 @@ class DeviceOAuth2TokenService : public OAuth2TokenService,
 
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
-  // Implementation of OAuth2TokenService.
-  bool RefreshTokenIsAvailable(const std::string& account_id) const override;
-
   // Pull the robot account ID from device policy.
   virtual std::string GetRobotAccountId() const;
 
@@ -71,18 +93,12 @@ class DeviceOAuth2TokenService : public OAuth2TokenService,
   void OnNetworkError(int response_code) override;
 
  protected:
-  // Implementation of OAuth2TokenService.
-  net::URLRequestContextGetter* GetRequestContext() override;
   void FetchOAuth2Token(RequestImpl* request,
                         const std::string& account_id,
                         net::URLRequestContextGetter* getter,
                         const std::string& client_id,
                         const std::string& client_secret,
                         const ScopeSet& scopes) override;
-  OAuth2AccessTokenFetcher* CreateAccessTokenFetcher(
-      const std::string& account_id,
-      net::URLRequestContextGetter* getter,
-      OAuth2AccessTokenConsumer* consumer) override;
 
  private:
   struct PendingRequest;
@@ -105,6 +121,21 @@ class DeviceOAuth2TokenService : public OAuth2TokenService,
     STATE_TOKEN_VALID,
   };
 
+  // Concrete Implementation of GetRequestContext for
+  // DeviceOAuth2TokenServiceDelegate.
+  net::URLRequestContextGetter* GetRequestContextImpl();
+
+  // Concrete Implementation of RefreshTokenIsAvailableImpl for
+  // DeviceOAuth2TokenServiceDelegate.
+  bool RefreshTokenIsAvailableImpl(const std::string& account_id) const;
+
+  // Concrete Implementation of CreateAccessTokenFetcher for
+  // DeviceOAuth2TokenServiceDelegate.
+  OAuth2AccessTokenFetcher* CreateAccessTokenFetcherImpl(
+      const std::string& account_id,
+      net::URLRequestContextGetter* getter,
+      OAuth2AccessTokenConsumer* consumer);
+
   // Invoked by CrosSettings when the robot account ID becomes available.
   void OnServiceAccountIdentityChanged();
 
@@ -145,6 +176,8 @@ class DeviceOAuth2TokenService : public OAuth2TokenService,
   scoped_refptr<net::URLRequestContextGetter> url_request_context_getter_;
   PrefService* local_state_;
 
+  DeviceOAuth2TokenServiceDelegate* device_oauth2_token_service_delegate_;
+
   // Current operational state.
   State state_;