Add robustness against OAuth2 Token requests getting canceled.

components/ntp_snippets/ntp_snippets_fetcher.cc

 // Copyright 2016 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.
 
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
 
 #include <stdlib.h>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 214 matching lines @@
     return;
   }
 
   locale_ = PosixLocaleFromBCP47Language(language_code);
   count_to_fetch_ = count;
 
   bool use_authentication = UsesAuthentication();
 
   if (use_authentication && signin_manager_->IsAuthenticated()) {
     // Signed-in: get OAuth token --> fetch snippets.
+    oauth_token_retried_ = false;

[Marc Treib, 2016/08/11 09:35:17]

You should also initialize this in the ctor

[jkrcal, 2016/08/11 10:03:56]

Done. 

I was wondering about it. In the current code, I always write before read. What
is the rule? Should I always initialize _everything_ to some sane value?

[Marc Treib, 2016/08/11 10:11:03]

Yes. I'm not sure if the style guide has a rule about this, but IMO it's a good
practice to never have uninitialized values - those are just asking for trouble.

[jkrcal, 2016/08/11 12:31:48]

Makes sense. Thanks.

     StartTokenRequest();
   } else if (use_authentication && signin_manager_->AuthInProgress()) {
     // Currently signing in: wait for auth to finish (the refresh token) -->
     //     get OAuth token --> fetch snippets.
     if (!waiting_for_refresh_token_) {
       // Wait until we get a refresh token.
       waiting_for_refresh_token_ = true;
       token_service_->AddObserver(this);
     }
   } else {
@@ skipping 184 matching lines @@
   DCHECK_EQ(oauth_request.get(), request)
       << "Got tokens from some previous request";
 
   FetchSnippetsAuthenticated(oauth_request->GetAccountId(), access_token);
 }
 
 void NTPSnippetsFetcher::OnGetTokenFailure(
     const OAuth2TokenService::Request* request,
     const GoogleServiceAuthError& error) {
   oauth_request_.reset();
-  DLOG(ERROR) << "Unable to get token: " << error.ToString()
-              << " - fetching the snippets without authentication.";

[Marc Treib, 2016/08/11 09:35:17]

Outdated documentation ftl :D

[jkrcal, 2016/08/11 10:03:56]

:)

+
+  if (!oauth_token_retried_ &&
+      error.state() == GoogleServiceAuthError::State::REQUEST_CANCELED) {
+    // The request (especially on startup) can get reset by loading the refresh
+    // token - do it one more time.
+    oauth_token_retried_ = true;
+    StartTokenRequest();
+    return;
+  }
+
+  DLOG(ERROR) << "Unable to get token: " << error.ToString();
   FetchFinished(
       OptionalSnippets(), FetchResult::OAUTH_TOKEN_ERROR,
       /*extra_message=*/base::StringPrintf(" (%s)", error.ToString().c_str()));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // OAuth2TokenService::Observer overrides
 void NTPSnippetsFetcher::OnRefreshTokenAvailable(
     const std::string& account_id) {
   // Only react on tokens for the account the user has signed in with.
   if (account_id != signin_manager_->GetAuthenticatedAccountId())
     return;
 
   token_service_->RemoveObserver(this);
   waiting_for_refresh_token_ = false;
+  oauth_token_retried_ = false;
   StartTokenRequest();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // URLFetcherDelegate overrides
 void NTPSnippetsFetcher::OnURLFetchComplete(const URLFetcher* source) {
   DCHECK_EQ(url_fetcher_.get(), source);
 
   const URLRequestStatus& status = source->GetStatus();
 
@@ skipping 103 matching lines @@
   }
   UMA_HISTOGRAM_ENUMERATION("NewTabPage.Snippets.FetchResult",
                             static_cast<int>(result),
                             static_cast<int>(FetchResult::RESULT_MAX));
 
   if (!snippets_available_callback_.is_null())
     snippets_available_callback_.Run(std::move(snippets));
 }
 
 }  // namespace ntp_snippets