Blimp OAuth2 token retreival on application start up.

blimp/client/core/blimp_client_context_impl.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/blimp_client_context_impl.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/threading/sequenced_task_runner_handle.h"
@@ skipping 63 matching lines @@
   delegate_ = delegate;
 }
 
 std::unique_ptr<BlimpContents> BlimpClientContextImpl::CreateBlimpContents() {
   std::unique_ptr<BlimpContents> blimp_contents =
       blimp_contents_manager_->CreateBlimpContents();
   delegate_->AttachBlimpContentsHelpers(blimp_contents.get());
   return blimp_contents;
 }
 
-void BlimpClientContextImpl::Connect(const std::string& client_auth_token) {
+void BlimpClientContextImpl::Connect() {
+  // Lazy initialization of IdentitySource.
+  if (!identity_source_) {
+    identity_source_ = base::MakeUnique<IdentitySource>(delegate_);
+    identity_source_->SetTokenCallback(
+        base::Bind(&BlimpClientContextImpl::ConnectToAssignmentSource,
+                   base::Unretained(this)));
+  }
+
+  // Start Blimp authentication flow. The OAuth2 token will be used in
+  // assignment source.
+  identity_source_->Connect();
+}
+
+void BlimpClientContextImpl::ConnectToAssignmentSource(
+    const std::string& client_auth_token) {
   if (!assignment_source_) {
     assignment_source_.reset(new AssignmentSource(
         GetAssignerURL(), io_thread_task_runner_, file_thread_task_runner_));
   }
 
   VLOG(1) << "Trying to get assignment.";
   assignment_source_->GetAssignment(
       client_auth_token,
       base::Bind(&BlimpClientContextImpl::ConnectWithAssignment,
                  weak_factory_.GetWeakPtr()));
@@ skipping 22 matching lines @@
   }
 
   io_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&ClientNetworkComponents::ConnectWithAssignment,
                  base::Unretained(net_components_.get()), assignment));
 }
 
 }  // namespace client
 }  // namespace blimp