content: don't show context menus for invisible WebContents

Bug: 855127
Change-Id: I2942e122373c210bd0bceaa59791e2619186f79b
Reviewed-on: https://chromium-review.googlesource.com/1175935Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583317}

content/browser/web_contents/web_contents_impl.cc

@@ -5052,6 +5052,12 @@ void WebContentsImpl::ShowContextMenu(RenderFrameHost* render_frame_host,
   if (showing_context_menu_)
     return;
 
+  // If the WebContents is not visible, don't show the context menu. This can
+  // happen if the renderer takes a while to return the right-click event back
+  // to the browser process and in the meantime the user switches tabs.
+  if (GetVisibility() != Visibility::VISIBLE)
+    return;
+
   ContextMenuParams context_menu_params(params);
   // Allow WebContentsDelegates to handle the context menu operation first.
   if (delegate_ && delegate_->HandleContextMenu(context_menu_params))