Add a content API for postMessage

content/browser/android/content_view_core_impl.h

Index: content/browser/android/content_view_core_impl.h
diff --git a/content/browser/android/content_view_core_impl.h b/content/browser/android/content_view_core_impl.h
index ed51f75f976da0aaa5eb9de551916385e3579eb3..2844abd0c5308e3a91f97b3c7a90233c589d58b5 100644
--- a/content/browser/android/content_view_core_impl.h
+++ b/content/browser/android/content_view_core_impl.h
@@ -165,6 +165,8 @@ class ContentViewCoreImpl : public ContentViewCore,
                           jstring script,
                           jobject callback,
                           jboolean start_renderer);
+  void PostMessageToFrame(JNIEnv* env, jobject obj, jstring frame_id,
+      jstring message, jstring source_origin, jstring target_origin);
   long GetNativeImeAdapter(JNIEnv* env, jobject obj);
   void SetFocus(JNIEnv* env, jobject obj, jboolean focused);
   void ScrollFocusedEditableNodeIntoView(JNIEnv* env, jobject obj);