Add a hang monitor for Pepper plugins

content/public/browser/web_contents_delegate.h

Index: content/public/browser/web_contents_delegate.h
diff --git a/content/public/browser/web_contents_delegate.h b/content/public/browser/web_contents_delegate.h
index 49e833ddd3c5fa976753d793d3f6b46e71de2bac..bb6282aa363d497b57ee71e5bf5934d88a780166 100644
--- a/content/public/browser/web_contents_delegate.h
+++ b/content/public/browser/web_contents_delegate.h
@@ -372,6 +372,19 @@ class CONTENT_EXPORT WebContentsDelegate {
   // Notification that a plugin has crashed.
   virtual void CrashedPlugin(WebContents* tab, const FilePath& plugin_path) {}
 
+  // Notication that the given plugin has hung or become unhung. This
+  // notification is only for Pepper plugins.
+  //
+  // The child_id is the unique child process ID from the plugin. Note that this
+  // ID is supplied by the renderer, so should be validated before it's used
+  // for anything in case there's an exploited renderer. The name will be
+  // provided if it is available, otherwise name will be empty and the
+  // implementation should use the patch to extract the plugin name.
+  virtual void PluginHungStatusChanged(WebContents* tab,
+                                       int plugin_child_id,
+                                       const FilePath& plugin_path,
+                                       bool is_hung) {}
+
   // Invoked when the preferred size of the contents has been changed.
   virtual void UpdatePreferredSize(WebContents* tab,
                                    const gfx::Size& pref_size) {}