Add a gyp flag to allow removing dependency on ppapi.

content/browser/renderer_host/render_message_filter.cc

Index: content/browser/renderer_host/render_message_filter.cc
diff --git a/content/browser/renderer_host/render_message_filter.cc b/content/browser/renderer_host/render_message_filter.cc
index 9d6b5b91d8104730610c7c56a308f7de3b2372d6..30c821c2dd171b36f14e10b6ffae2e37ad4df958 100644
--- a/content/browser/renderer_host/render_message_filter.cc
+++ b/content/browser/renderer_host/render_message_filter.cc
@@ -385,6 +385,7 @@ bool RenderMessageFilter::OnMessageReceived(const IPC::Message& message,
     IPC_MESSAGE_HANDLER(ViewHostMsg_DownloadUrl, OnDownloadUrl)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_OpenChannelToPlugin,
                                     OnOpenChannelToPlugin)
+#if defined(ENABLE_PLUGINS)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(ViewHostMsg_OpenChannelToPepperPlugin,
                                     OnOpenChannelToPepperPlugin)
     IPC_MESSAGE_HANDLER(ViewHostMsg_DidCreateOutOfProcessPepperInstance,
@@ -393,6 +394,7 @@ bool RenderMessageFilter::OnMessageReceived(const IPC::Message& message,
                         OnDidDeleteOutOfProcessPepperInstance)
     IPC_MESSAGE_HANDLER(ViewHostMsg_OpenChannelToPpapiBroker,
                         OnOpenChannelToPpapiBroker)
+#endif
     IPC_MESSAGE_HANDLER_GENERIC(ViewHostMsg_UpdateRect,
         render_widget_helper_->DidReceiveBackingStoreMsg(message))
     IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateIsDelayed, OnUpdateIsDelayed)