Implement touch events for site-isolation.

content/browser/renderer_host/render_widget_host_view_base.h

Index: content/browser/renderer_host/render_widget_host_view_base.h
diff --git a/content/browser/renderer_host/render_widget_host_view_base.h b/content/browser/renderer_host/render_widget_host_view_base.h
index 9a2e25bcc2b04abc937a4dd588c51b04d152236b..60957cc6ac871233d02d020d74eeba2e718cd378 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -361,6 +361,9 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   virtual void LockCompositingSurface() = 0;
   virtual void UnlockCompositingSurface() = 0;
 
+  virtual void RegisterSurfaceNamespaceId() {}

[piman, 2016/02/25 21:27:21]

Does this need to be virtual? AFAICT, the only callers are:
- browser_plugin_guest.cc and web_contents_impl.cc, which call it on the
concrete type
- RWHVChildFrame's constructor, which concerns me - calling a virtual method
from a constructor is dangerous and can cause subtle bugs.

[wjmaclean, 2016/02/28 19:45:03]

No, we can make it concrete on RenderWidgetHostViewChildFrame.

Done.

+  virtual void UnregisterSurfaceNamespaceId() {}
+
 #if defined(OS_MACOSX)
   // Does any event handling necessary for plugin IME; should be called after
   // the plugin has already had a chance to process the event. If plugin IME is