Add GetMinimumSize() for Borders, and make LabelButton auto-size to at least as

ash/system/tray/tray_details_view.cc

Index: ash/system/tray/tray_details_view.cc
===================================================================
--- ash/system/tray/tray_details_view.cc	(revision 236640)
+++ ash/system/tray/tray_details_view.cc	(working copy)
@@ -53,6 +53,10 @@
     return gfx::Insets(0, 0, 1, 0);
   }
 
+  virtual gfx::Size GetMinimumSize() const OVERRIDE {
+    return gfx::Size(0, 1);
+  }
+
   bool visible_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollBorder);