Clean up GetURLLoaderFactory to O2TS

This CL is a part of moving access token management to
OAuth2AccessTokenManager.

It cleans up GetURLLoaderFactory as StartRequest* APIs
were moved to OAuth2AccessTokenManager and they access
to SharedURLLoaderFactory through |delegate_| without
helper API.

Bug: 967598
Change-Id: I22db6c4ea985b3c195ea93e3b6fa518fe25ff8ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1672090
Commit-Queue: Julie Jeongeun Kim <jkim@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671952}

google_apis/gaia/oauth2_token_service.cc

@@ -156,11 +156,6 @@ OAuth2TokenService::StartRequestForClient(
                                                client_secret, scopes, consumer);
 }
 
-scoped_refptr<network::SharedURLLoaderFactory>
-OAuth2TokenService::GetURLLoaderFactory() const {
-  return delegate_->GetURLLoaderFactory();
-}
-
 std::unique_ptr<OAuth2TokenService::Request>
 OAuth2TokenService::StartRequestWithContext(
     const CoreAccountId& account_id,

google_apis/gaia/oauth2_token_service.h

@@ -139,7 +139,7 @@ class OAuth2TokenService : public OAuth2TokenServiceObserver {
 
   // This method does the same as |StartRequest| except it uses the
   // URLLoaderfactory given by |url_loader_factory| instead of using the one
-  // returned by |GetURLLoaderFactory| implemented by derived classes.
+  // returned by Delegate::GetURLLoaderFactory().
   // Deprecated. It's moved to OAuth2AccessTokenManager.
   std::unique_ptr<Request> StartRequestWithContext(
       const CoreAccountId& account_id,
@@ -299,10 +299,6 @@ class OAuth2TokenService : public OAuth2TokenServiceObserver {
  private:
   friend class OAuth2TokenServiceDelegate;
 
-  // Provide a URLLoaderFactory used for fetching access tokens with the
-  // |StartRequest| method.
-  scoped_refptr<network::SharedURLLoaderFactory> GetURLLoaderFactory() const;
-
   std::unique_ptr<OAuth2TokenServiceDelegate> delegate_;
 
   // The depth of batch changes.