Switch DomAutomationController to be a RenderFrameObserver.

content/common/frame_messages.h

Index: content/common/frame_messages.h
diff --git a/content/common/frame_messages.h b/content/common/frame_messages.h
index 6f9b3a1df6a82113107f2d1064a1f1b4d90b6d8f..9f6679f0da3cbf6a7c2c85a5fcaa1fb7b58b52ba 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -175,6 +175,15 @@ IPC_MESSAGE_ROUTED5(FrameHostMsg_DidFailLoadWithError,
                     int /* error_code */,
                     base::string16 /* error_description */)
 
+// Following message is used to communicate the values received by the
+// callback binding the JS to Cpp.
+// An instance of browser that has an automation host listening to it can
+// have a javascript send a native value (string, number, boolean) to the
+// listener in Cpp. (DomAutomationController)
+IPC_MESSAGE_ROUTED2(FrameHostMsg_DomOperationResponse,
+                    std::string  /* json_string */,
+                    int  /* automation_id */)
+
 // Sent to the browser when the renderer detects it is blocked on a pepper
 // plugin message for too long. This is also sent when it becomes unhung
 // (according to the value of is_hung). The browser can give the user the