Fix sizing issues in the tab modal signin flow.

chrome/browser/ui/signin_view_controller_delegate.h

Index: chrome/browser/ui/signin_view_controller_delegate.h
diff --git a/chrome/browser/ui/signin_view_controller_delegate.h b/chrome/browser/ui/signin_view_controller_delegate.h
index 85ada3281fd8ccb07e4bd70637a66a20a8e5f11e..119088907a7a2782a1e22827501207ce15068078 100644
--- a/chrome/browser/ui/signin_view_controller_delegate.h
+++ b/chrome/browser/ui/signin_view_controller_delegate.h
@@ -52,11 +52,20 @@ class SigninViewControllerDelegate : public content::WebContentsDelegate {
   // the user, requesting either a back navigation or closing the dialog.
   void HandleNavigationButtonClicked(const base::ListValue* args);
 
+  // Handles the web ui message sent when the html content is done being laid
+  // out and it's time to resize the native view hosting it to fit. |args| is
+  // a single integer value for the height the native view should resize to.
+  void HandleResizeNativeView(const base::ListValue* args);
+
   // This will be called by this base class when the tab-modal window must be
   // closed. This should close the platform-specific window that is currently
   // showing the sign in flow or the sync confirmation dialog.
   virtual void PerformClose() = 0;
 
+  // This will be called by the base class to request a resize of the native
+  // view hosting the content to |height|.
+  virtual void ResizeNativeView(int height) = 0;
+
  private:
   bool CanGoBack(content::WebContents* web_ui_web_contents) const;