Implement pointer lock API for out-of-process iframes.

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index 25f5a9693d529436ca56c1deb9c60d8790b2060c..5d465ef47139619dbbfa2bf9586a4c2c0d899db9 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -1395,6 +1395,10 @@ class CONTENT_EXPORT WebContentsImpl
   // by the TextInputManager in the outer WebContents.
   std::unique_ptr<TextInputManager> text_input_manager_;
 
+  // Stores the RenderWidgetHost that currently holds a mouse lock or nullptr if
+  // there's no RenderWidgetHost holding a lock.
+  RenderWidgetHostImpl* mouse_lock_widget_;
+
   base::WeakPtrFactory<WebContentsImpl> loading_weak_factory_;
   base::WeakPtrFactory<WebContentsImpl> weak_factory_;