Makes browser resize content when root bounds change

mandoline/ui/browser/browser_ui.h

Index: mandoline/ui/browser/browser_ui.h
diff --git a/mandoline/ui/browser/browser_ui.h b/mandoline/ui/browser/browser_ui.h
index 978943c51a89f62fbe0806adf46d3e47693f2acb..5e155c11bef25801ae8a5696cde25abda5cc804b 100644
--- a/mandoline/ui/browser/browser_ui.h
+++ b/mandoline/ui/browser/browser_ui.h
@@ -20,6 +20,9 @@ class BrowserUI {
   static BrowserUI* Create(Browser* browser, mojo::Shell* shell);
 
   // Called when the Browser UI is embedded within the specified view.
+  // BrowserUI is destroyed prior to |root| being destroyed. That is, the
+  // BrowserUI implementations can assume |root| is never deleted out from under
+  // them.
   virtual void Init(mojo::View* root, mojo::View* content) = 0;
 };