Add robustness against OAuth2 Token requests getting canceled.

components/ntp_snippets/ntp_snippets_fetcher.cc

Index: components/ntp_snippets/ntp_snippets_fetcher.cc
diff --git a/components/ntp_snippets/ntp_snippets_fetcher.cc b/components/ntp_snippets/ntp_snippets_fetcher.cc
index d8ca50902d94038d5d08f33d7b35d85b6716b5f6..6211c4d42afaa0fca40f0f72f862272dd495c292 100644
--- a/components/ntp_snippets/ntp_snippets_fetcher.cc
+++ b/components/ntp_snippets/ntp_snippets_fetcher.cc
@@ -232,6 +232,7 @@ void NTPSnippetsFetcher::FetchSnippetsFromHosts(
 
   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) -->
@@ -436,8 +437,17 @@ 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Outdated documentation ftl :D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()));
@@ -453,6 +463,7 @@ void NTPSnippetsFetcher::OnRefreshTokenAvailable(
 
   token_service_->RemoveObserver(this);
   waiting_for_refresh_token_ = false;
+  oauth_token_retried_ = false;
   StartTokenRequest();
 }