Reland http://codereview.chromium.org/7292033

webkit/plugins/ppapi/ppapi_plugin_instance.cc

 // Copyright (c) 2011 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 "webkit/plugins/ppapi/ppapi_plugin_instance.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
@@ skipping 682 matching lines @@
             PPP_INPUT_EVENT_INTERFACE));
   }
   return !!plugin_input_event_interface_;
 }
 
 bool PluginInstance::LoadMessagingInterface() {
   if (!checked_for_plugin_messaging_interface_) {
     checked_for_plugin_messaging_interface_ = true;
     plugin_messaging_interface_ =
         static_cast<const PPP_Messaging*>(module_->GetPluginInterface(
-            PPP_MESSAGING_INTERFACE));
+            PPP_MESSAGING_INTERFACE_1_0));
+    // TODO(dmichael): Remove support for 0.1.
+    if (!plugin_messaging_interface_) {
+      plugin_messaging_interface_ =
+          static_cast<const PPP_Messaging*>(module_->GetPluginInterface(
+              PPP_MESSAGING_INTERFACE_0_1));
+    }
   }
 
   return !!plugin_messaging_interface_;
 }
 
 bool PluginInstance::LoadPdfInterface() {
   if (!plugin_pdf_interface_) {
     plugin_pdf_interface_ =
         static_cast<const PPP_Pdf*>(module_->GetPluginInterface(
             PPP_PDF_INTERFACE));
@@ skipping 832 matching lines @@
   }
   delegate()->ZoomLimitsChanged(minimum_factor, maximium_factor);
 }
 
 void PluginInstance::PostMessage(PP_Instance instance, PP_Var message) {
   message_channel_->PostMessageToJavaScript(message);
 }
 
 }  // namespace ppapi
 }  // namespace webkit