Unnecessary 'translate to English' option is displayed in context menu in PDF.

chrome/browser/renderer_context_menu/render_view_context_menu.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 "chrome/browser/renderer_context_menu/render_view_context_menu.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 1157 matching lines @@
       if (embedder_web_contents_->GetController().GetVisibleEntry() == NULL)
         return false;
       // Disabled if no browser is associated (e.g. desktop notifications).
       if (chrome::FindBrowserWithWebContents(embedder_web_contents_) == NULL)
         return false;
       return true;
 
     case IDC_CONTENT_CONTEXT_TRANSLATE: {
       ChromeTranslateClient* chrome_translate_client =
           ChromeTranslateClient::FromWebContents(embedder_web_contents_);
-      if (!chrome_translate_client)
+      // If no |chrome_translate_client| attached with this WebContents or we're
+      // viewing in a MimeHandlerViewGuest translate will be disabled.
+      if (!chrome_translate_client ||
+          !!extensions::MimeHandlerViewGuest::FromWebContents(
+              source_web_contents_)) {
         return false;
+      }
       std::string original_lang =
           chrome_translate_client->GetLanguageState().original_language();
       std::string target_lang = g_browser_process->GetApplicationLocale();
       target_lang =
           translate::TranslateDownloadManager::GetLanguageCode(target_lang);
       // Note that we intentionally enable the menu even if the original and
       // target languages are identical.  This is to give a way to user to
       // translate a page that might contains text fragments in a different
       // language.
       return ((params_.edit_flags & WebContextMenuData::CanTranslate) != 0) &&
@@ skipping 815 matching lines @@
   source_web_contents_->GetRenderViewHost()->
       ExecuteMediaPlayerActionAtLocation(location, action);
 }
 
 void RenderViewContextMenu::PluginActionAt(
     const gfx::Point& location,
     const WebPluginAction& action) {
   source_web_contents_->GetRenderViewHost()->
       ExecutePluginActionAtLocation(location, action);
 }