Added code to disable 'paste' if nothing is present in clipboard to paste.

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 1352 matching lines @@
     case IDC_CONTENT_CONTEXT_REDO:
       return !!(params_.edit_flags & WebContextMenuData::CanRedo);
 
     case IDC_CONTENT_CONTEXT_CUT:
       return !!(params_.edit_flags & WebContextMenuData::CanCut);
 
     case IDC_CONTENT_CONTEXT_COPY:
       return !!(params_.edit_flags & WebContextMenuData::CanCopy);
 
     case IDC_CONTENT_CONTEXT_PASTE:
-    case IDC_CONTENT_CONTEXT_PASTE_AND_MATCH_STYLE:
-      return !!(params_.edit_flags & WebContextMenuData::CanPaste);
-
+    case IDC_CONTENT_CONTEXT_PASTE_AND_MATCH_STYLE: {
+      std::vector<base::string16> types;
+      bool ignore;
+      ui::Clipboard::GetForCurrentThread()->ReadAvailableTypes(

[darin (slow to review), 2014/08/06 16:31:33]

This is potentially an expensive call, right? Should we worry about this janking
up the UI thread of the browser? Perhaps there is no other way to implement this
behavior though?

+          ui::CLIPBOARD_TYPE_COPY_PASTE, &types, &ignore);
+      return !types.empty();
+    }
     case IDC_CONTENT_CONTEXT_DELETE:
       return !!(params_.edit_flags & WebContextMenuData::CanDelete);
 
     case IDC_CONTENT_CONTEXT_SELECTALL:
       return !!(params_.edit_flags & WebContextMenuData::CanSelectAll);
 
     case IDC_CONTENT_CONTEXT_OPENLINKOFFTHERECORD:
       return !browser_context_->IsOffTheRecord() &&
              params_.link_url.is_valid() &&
              incognito_avail != IncognitoModePrefs::DISABLED;
@@ skipping 663 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);
 }