Fix sizing issues in the tab modal signin flow.

chrome/browser/ui/signin_view_controller_delegate.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_SIGNIN_VIEW_CONTROLLER_DELEGATE_H_
 #define CHROME_BROWSER_UI_SIGNIN_VIEW_CONTROLLER_DELEGATE_H_
 
 #include "chrome/browser/ui/profile_chooser_constants.h"
 #include "content/public/browser/web_contents_delegate.h"
 
@@ skipping 34 matching lines @@
   void ResetSigninViewControllerDelegate();
 
   // content::WebContentsDelegate
   void LoadingStateChanged(content::WebContents* source,
                            bool to_different_document) override;
 
   // Handles the web ui message sent when the navigation button is clicked by
   // 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;
 
   SigninViewController* signin_view_controller_;  // Not owned.
   content::WebContents* web_contents_;  // Not owned.
   DISALLOW_COPY_AND_ASSIGN(SigninViewControllerDelegate);
 };
 
 #endif  // CHROME_BROWSER_UI_SIGNIN_VIEW_CONTROLLER_DELEGATE_H_