Add an error message to the Javascript console when the NaCl plugin is blocked,

chrome/renderer/chrome_content_renderer_client.cc

 // Copyright (c) 2012 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/renderer/chrome_content_renderer_client.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 69 matching lines @@
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebURL.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebURLError.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebURLRequest.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "webkit/plugins/npapi/plugin_list.h"
 #include "webkit/plugins/ppapi/plugin_module.h"
 #include "webkit/plugins/ppapi/ppapi_interface_factory.h"
 
 using WebKit::WebCache;
+using WebKit::WebConsoleMessage;
 using WebKit::WebDataSource;
 using WebKit::WebDocument;
 using WebKit::WebFrame;
 using WebKit::WebPlugin;
 using WebKit::WebPluginParams;
 using WebKit::WebSecurityOrigin;
 using WebKit::WebSecurityPolicy;
 using WebKit::WebString;
 using WebKit::WebURL;
 using WebKit::WebURLError;
@@ skipping 320 matching lines @@
       // NaCl tests for the plugin work.
       is_nacl_enabled = true;
     }
     if (is_nacl_plugin || is_nacl_mime_type) {
       if (!IsNaClAllowed(plugin,
                          url,
                          actual_mime_type,
                          is_nacl_mime_type,
                          is_nacl_enabled,
                          params)) {
+        frame->addMessageToConsole(
+            WebConsoleMessage(
+                WebConsoleMessage::LevelError,
+                "Only unpacked extensions and apps installed from the Chrome"
+                " Web Store can load NaCl modules without enabling Native"
+                " Client in about:flags."));
         return BlockedPlugin::Create(
             render_view, frame, params, plugin, group.get(),
             IDR_BLOCKED_PLUGIN_HTML, IDS_PLUGIN_BLOCKED, false, false);
       }
     }
 
     return render_view->CreatePlugin(frame, plugin, params);
   }
 
   observer->DidBlockContentType(
@@ skipping 379 matching lines @@
     webkit::ppapi::PpapiInterfaceFactoryManager* factory_manager) {
   factory_manager->RegisterFactory(ChromePPAPIInterfaceFactory);
 }
 
 bool ChromeContentRendererClient::AllowSocketAPI(const GURL& url) {
   return allowed_socket_origins_.find(url.host()) !=
       allowed_socket_origins_.end();
 }
 
 }  // namespace chrome