Add a warning for the deprecation of content-initiated data URL navigations

content/browser/frame_host/navigation_handle_impl.cc

Index: content/browser/frame_host/navigation_handle_impl.cc
diff --git a/content/browser/frame_host/navigation_handle_impl.cc b/content/browser/frame_host/navigation_handle_impl.cc
index 74e0b202c6f005ffc79bb32c909b01bb847c83f2..e0cce691db21752db0699c8128b27190711c3ed8 100644
--- a/content/browser/frame_host/navigation_handle_impl.cc
+++ b/content/browser/frame_host/navigation_handle_impl.cc
@@ -638,6 +638,14 @@ void NavigationHandleImpl::DidCommitNavigation(
   } else {
     state_ = DID_COMMIT;
   }
+
+  if (url_.SchemeIs(url::kDataScheme) && IsInMainFrame() &&
+      IsRendererInitiated()) {
+    GetRenderFrameHost()->AddMessageToConsole(
+        CONSOLE_MESSAGE_LEVEL_WARNING,
+        "Upcoming versions will block content-initiated top frame navigations "
+        "to data: URLs. For more information, see https://goo.gl/BaZAea.");
+  }
 }
 
 void NavigationHandleImpl::Transfer() {