[Desktop] Add diagnostics about loading the refresh tokens.

google_apis/gaia/oauth2_token_service_delegate.h

Index: google_apis/gaia/oauth2_token_service_delegate.h
diff --git a/google_apis/gaia/oauth2_token_service_delegate.h b/google_apis/gaia/oauth2_token_service_delegate.h
index 1f6477bc42df6c9e9a252a20f51a43578eb2cc87..d01b9ae0eebdc74bdd8a08431531ded229d8d532 100644
--- a/google_apis/gaia/oauth2_token_service_delegate.h
+++ b/google_apis/gaia/oauth2_token_service_delegate.h
@@ -20,6 +20,16 @@ class URLRequestContextGetter;
 // CreateAccessTokenFetcher properly.
 class OAuth2TokenServiceDelegate {
  public:
+  enum LoadCredentialsState {
+    LOAD_CREDENTIALS_UNKNOWN,
+    LOAD_CREDENTIALS_NOT_STARTED,
+    LOAD_CREDENTIALS_IN_PROGRESS,
+    LOAD_CREDENTIALS_FINISHED_WITH_SUCCESS,
+    LOAD_CREDENTIALS_FINISHED_WITH_DB_ERRORS,
+    LOAD_CREDENTIALS_FINISHED_WITH_DECRYPT_ERRORS,
+    LOAD_CREDENTIALS_FINISHED_WITH_UNKNOWN_ERRORS,
+  };
+
   OAuth2TokenServiceDelegate();
   virtual ~OAuth2TokenServiceDelegate();
 
@@ -58,6 +68,11 @@ class OAuth2TokenServiceDelegate {
   // a nullptr otherwise.
   virtual const net::BackoffEntry* BackoffEntry() const;
 
+  // Diagnostic methods
+
+  // Returns the state of the load credentials operation.
+  virtual LoadCredentialsState GetLoadCredentialsState() const;
+
  protected:
   // Called by subclasses to notify observers.
   virtual void FireRefreshTokenAvailable(const std::string& account_id);