app_shell: Add version number in user agent

extensions/shell/common/shell_content_client.cc

 // Copyright 2014 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 "extensions/shell/common/shell_content_client.h"
 
 #include "base/strings/string_piece.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/public/common/user_agent.h"
 #include "extensions/common/constants.h"
+#include "extensions/shell/common/version.h"  // Generated file.
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
 
 #if !defined(DISABLE_NACL)
 #include "base/base_paths.h"
 #include "base/files/file_path.h"
 #include "base/path_service.h"
 #include "components/nacl/common/nacl_constants.h"
 #include "content/public/common/pepper_plugin_info.h"
 #include "ppapi/native_client/src/trusted/plugin/ppapi_entrypoints.h"
@@ skipping 55 matching lines @@
 void ShellContentClient::AddAdditionalSchemes(
     std::vector<std::string>* standard_schemes,
     std::vector<std::string>* savable_schemes) {
   standard_schemes->push_back(kExtensionScheme);
   savable_schemes->push_back(kExtensionScheme);
   standard_schemes->push_back(kExtensionResourceScheme);
   savable_schemes->push_back(kExtensionResourceScheme);
 }
 
 std::string ShellContentClient::GetUserAgent() const {
-  // TODO(derat): Figure out what this should be for app_shell and determine
-  // whether we need to include a version number to placate browser sniffing.
-  return content::BuildUserAgentFromProduct("Chrome");
+  // Must contain a user agent string for version sniffing. For example,
+  // pluginless WebRTC Hangouts checks the Chrome version number.
+  return content::BuildUserAgentFromProduct("Chrome/" PRODUCT_VERSION);
 }
 
 base::string16 ShellContentClient::GetLocalizedString(int message_id) const {
   return l10n_util::GetStringUTF16(message_id);
 }
 
 base::StringPiece ShellContentClient::GetDataResource(
     int resource_id,
     ui::ScaleFactor scale_factor) const {
   return ResourceBundle::GetSharedInstance().GetRawDataResourceForScale(
       resource_id, scale_factor);
 }
 
 base::RefCountedStaticMemory* ShellContentClient::GetDataResourceBytes(
     int resource_id) const {
   return ResourceBundle::GetSharedInstance().LoadDataResourceBytes(resource_id);
 }
 
 gfx::Image& ShellContentClient::GetNativeImageNamed(int resource_id) const {
   return ResourceBundle::GetSharedInstance().GetNativeImageNamed(resource_id);
 }
 
 }  // namespace extensions