Implement signin using webview

extensions/browser/extension_function.h

 // Copyright 2013 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.
 
 #ifndef EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_
 #define EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_
 
 #include <list>
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/process/process.h"
 #include "base/sequenced_task_runner_helpers.h"
+#include "base/strings/string_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/console_message_level.h"
 #include "extensions/browser/extension_function_histogram_value.h"
 #include "extensions/browser/info_map.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/features/feature.h"
 #include "ipc/ipc_message.h"
 
 class ExtensionFunction;
 class UIThreadExtensionFunction;
@@ skipping 183 matching lines @@
   const std::string& name() const { return name_; }
 
   void set_profile_id(void* profile_id) { profile_id_ = profile_id; }
   void* profile_id() const { return profile_id_; }
 
   void set_extension(
       const scoped_refptr<const extensions::Extension>& extension) {
     extension_ = extension;
   }
   const extensions::Extension* extension() const { return extension_.get(); }
-  const std::string& extension_id() const { return extension_->id(); }
+  std::string extension_id() const {
+    return extension_ ? extension_->id() : base::EmptyString();

[Fady Samuel, 2014/10/21 21:32:57]

I think Ben Kalman should review this change. It might make sense to break down
this CL into multiple CLs as there are many stakeholders here.

[guohui, 2014/10/22 15:35:33]

Done.

+  }
 
   void set_request_id(int request_id) { request_id_ = request_id; }
   int request_id() { return request_id_; }
 
   void set_source_url(const GURL& source_url) { source_url_ = source_url; }
   const GURL& source_url() { return source_url_; }
 
   void set_has_callback(bool has_callback) { has_callback_ = has_callback; }
   bool has_callback() { return has_callback_; }
 
@@ skipping 374 matching lines @@
   virtual bool RunSync() = 0;
 
   // ValidationFailure override to match RunSync().
   static bool ValidationFailure(SyncIOThreadExtensionFunction* function);
 
  private:
   virtual ResponseAction Run() override;
 };
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_