Enable posting a message from JS to Android webview.

android_webview/renderer/aw_content_renderer_client.cc

Index: android_webview/renderer/aw_content_renderer_client.cc
diff --git a/android_webview/renderer/aw_content_renderer_client.cc b/android_webview/renderer/aw_content_renderer_client.cc
index 24349cdd9a00387da9f84c3362e15d73c2aa419a..37710597f18b53771ce9f39663bd6778447767d6 100644
--- a/android_webview/renderer/aw_content_renderer_client.cc
+++ b/android_webview/renderer/aw_content_renderer_client.cc
@@ -8,6 +8,7 @@
 #include "android_webview/common/render_view_messages.h"
 #include "android_webview/common/url_constants.h"
 #include "android_webview/renderer/aw_key_systems.h"
+#include "android_webview/renderer/aw_message_port_client.h"
 #include "android_webview/renderer/aw_permission_client.h"
 #include "android_webview/renderer/aw_render_frame_ext.h"
 #include "android_webview/renderer/aw_render_view_ext.h"
@@ -122,6 +123,7 @@ void AwContentRendererClient::RenderFrameCreated(
   new AwPermissionClient(render_frame);
   new PrintRenderFrameObserver(render_frame);
   new AwRenderFrameExt(render_frame);
+  new AwMessagePortClient(render_frame);
 
   // TODO(jam): when the frame tree moves into content and parent() works at
   // RenderFrame construction, simplify this by just checking parent().