WebUI TaskManager: Add method to set minimum window size on HTMLDialog.

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index 265ae361f4c3746201ce42a522ca13c3eebe6a46..554d4c3f4fa26d5dc71f3be00cb26e5928c50a7c 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -315,6 +315,9 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   void SetBounds(const gfx::Rect& bounds);
   void SetSize(const gfx::Size& size);
 
+  // Sizes the window to the specified size and centerizes it.
+  void CenterWindow(const gfx::Size& size);
+
   // Like SetBounds(), but ensures the Widget is fully visible on screen,
   // resizing and/or repositioning as necessary. This is only useful for
   // non-child widgets.