Force resize event to be sent to OOPIF subframes when main frame resizes.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index d96814515a88d7f2fa6fec2e54d0288d5af9c00f..ef3df07a00fa46e42d3c5b07343d4f42d20d2c89 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1881,6 +1881,12 @@ void WebContentsImpl::RenderWidgetWasResized(
   GetScreenInfo(&screen_info);
   SendPageMessage(new PageMsg_UpdateScreenInfo(MSG_ROUTING_NONE, screen_info));
 
+  // Send resize message to subframes.
+  for (RenderWidgetHostView* view : GetRenderWidgetHostViewsInTree()) {
+    if (view != rfh->GetView())
+      view->GetRenderWidgetHost()->WasResized();
+  }
+
   for (auto& observer : observers_)
     observer.MainFrameWasResized(width_changed);
 }