Blimp OAuth2 token retreival on application start up.

blimp/client/core/session/identity_source.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 <blimp/client/core/session/identity_source.h>
+
+namespace blimp {
+namespace client {
+
+namespace {
+// OAuth2 token scope.
+const char kOAuth2TokenScope[] =
+    "https://www.googleapis.com/auth/userinfo.email";
+}  // namespace
+
+IdentitySource::IdentitySource(
+    std::unique_ptr<IdentityProvider> identity_provider)
+    : OAuth2TokenService::Consumer("blimp_client"),
+      identity_provider_(std::move(identity_provider)) {
+  DCHECK(identity_provider_);
+
+  identity_provider_->AddObserver(this);
+}
+
+IdentitySource::~IdentitySource() {
+  identity_provider_->RemoveActiveAccountRefreshTokenObserver(this);
+  identity_provider_->RemoveObserver(this);
+}
+
+void IdentitySource::Connect() {
+  const std::string& account_id = identity_provider_->GetActiveAccountId();
+
+  // User must sign in first.
+  if (account_id.empty()) {
+    delegate_->OnError(BlimpClientContextDelegate::NOT_SIGNED_IN);
+    return;
+  }
+
+  account_id_ = account_id;
+  FetchAuthToken();
+}
+
+void IdentitySource::SetDelegate(BlimpClientContextDelegate* delegate) {
+  delegate_ = delegate;
+}
+
+void IdentitySource::OnGetTokenSuccess(
+    const OAuth2TokenService::Request* request,
+    const std::string& access_token,
+    const base::Time& expiration_time) {
+  token_request_.reset();
+  // TODO(xingliu): Use the token to connect.
+}
+
+// Fail to get the token after retries attempts in native layer and Java layer.
+void IdentitySource::OnGetTokenFailure(
+    const OAuth2TokenService::Request* request,
+    const GoogleServiceAuthError& error) {
+  token_request_.reset();
+  DCHECK(delegate_);
+  delegate_->OnError(BlimpClientContextDelegate::OAUTH_TOKEN_FAIL);
+}
+
+void IdentitySource::OnRefreshTokenAvailable(const std::string& account_id) {

[nyquist, 2016/08/12 05:47:04]

Should this also reset |token_request_|?

[xingliu, 2016/08/12 17:58:27]

Investigate the code a little bit, I think we shouldn't do this here.

Request(OAuth2TokenService::RequestImpl) wraps Consumer(implemented by
IdentitySource) which gives token callbacks, reset it here will eat the
OnGetTokenFailure callback if a refresh happens in the middle of the request.

+  if (account_id != account_id_) {
+    return;
+  }
+
+  identity_provider_->RemoveActiveAccountRefreshTokenObserver(this);
+  FetchAuthToken();
+}
+
+void IdentitySource::FetchAuthToken() {
+  OAuth2TokenService* token_service = identity_provider_->GetTokenService();
+  DCHECK(token_service);
+
+  if (token_service->RefreshTokenIsAvailable(account_id_)) {
+    OAuth2TokenService::ScopeSet scopes;
+    scopes.insert(kOAuth2TokenScope);
+    token_request_ = token_service->StartRequest(account_id_, scopes, this);
+  } else {
+    identity_provider_->AddActiveAccountRefreshTokenObserver(this);
+  }
+}
+
+}  // namespace client
+}  // namespace blimp