Follow-up on http://codereview.chromium.org/2861019 to address Powel's commen...

chrome/browser/automation/automation_provider.cc

 // Copyright (c) 2010 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 "chrome/browser/automation/automation_provider.h"
 
 #include <set>
 
 #include "app/l10n_util.h"
 #include "app/message_box_flags.h"
 #include "base/callback.h"
 #include "base/file_path.h"
 #include "base/file_version_info.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
+#include "base/json/string_escape.h"
 #include "base/keyboard_codes.h"
 #include "base/message_loop.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/stl_util-inl.h"
 #include "base/string_util.h"
 #include "base/thread.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/app/chrome_dll_resource.h"
@@ skipping 1576 matching lines @@
   if (args->GetInteger(L"width", &width))
     rect.set_width(width);
   if (args->GetInteger(L"height", &height))
     rect.set_height(height);
   browser->window()->SetBounds(rect);
   AutomationMsg_SendJSONRequest::WriteReplyParams(
       reply_message, std::string("{}"), true);
   Send(reply_message);
 }
 
-std::string AutomationProvider::JSONErrorString(std::string err) {
-  std::string prefix = "{\"error\": \"";
-  std::string no_quote_err = err;
-  std::string suffix = "\"}";
-
-  // Don't allow input string to break JSON by embedding quotes.
-  // Try and make sure the input string won't break json quoting rules.
-  if (no_quote_err.find("\"") != std::string::npos)
-    no_quote_err = "unhappy about embedded quote in error string";
-
-  return prefix + no_quote_err + suffix;
-}
-
 // Sample json input: { "command": "GetBrowserInfo" }
 // Refer to GetBrowserInfo() in chrome/test/pyautolib/pyauto.py for
 // sample json output.
 void AutomationProvider::GetBrowserInfo(Browser* browser,
                                         DictionaryValue* args,
                                         IPC::Message* reply_message) {
   std::string json_return;
   bool reply_return = true;
 
   DictionaryValue* properties = new DictionaryValue;
@@ skipping 600 matching lines @@
                                 SavePackage::SAVE_AS_ONLY_HTML)) {
       json_return = JSONErrorString("Could not initiate SavePage");
     } else {
       // The observer will delete itself when done.
       new SavePackageNotificationObserver(tab_contents->save_package(),
                                           this, reply_message);
       return;
     }
   }
 
-  // if we get here, error.
+  // If we get here, error.
   DCHECK(!json_return.empty());
   AutomationMsg_SendJSONRequest::WriteReplyParams(
       reply_message, json_return, false);
   Send(reply_message);
 }
 
+/* static */
+std::string AutomationProvider::JSONErrorString(std::string err) {
+  std::string prefix = "{\"error\": \"";
+  std::string no_quote_err;
+  std::string suffix = "\"}";
+
+  base::JsonDoubleQuote(err, false, &no_quote_err);
+  return prefix + no_quote_err + suffix;
+}
+
 void AutomationProvider::SendJSONRequest(int handle,
                                          std::string json_request,
                                          IPC::Message* reply_message) {
   Browser* browser = NULL;
   std::string error_string;
   scoped_ptr<Value> values;
 
   // Basic error checking.
   if (browser_tracker_->ContainsHandle(handle)) {
     browser = browser_tracker_->GetResource(handle);
@@ skipping 1242 matching lines @@
 }
 
 void AutomationProvider::WaitForPopupMenuToOpen(IPC::Message* reply_message) {
   NOTIMPLEMENTED();
 }
 #endif  // !defined(TOOLKIT_VIEWS)
 
 void AutomationProvider::ResetToDefaultTheme() {
   profile_->ClearTheme();
 }