It turns out I had the sense of the GetLocalBounds bool wrong everywhere, so ...

views/controls/slider/slider.cc

 // Copyright (c) 2010 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.
 
 #include "views/controls/slider/slider.h"
 
 #include <string>
 
 #include "views/controls/slider/native_slider_wrapper.h"
 #include "views/controls/native/native_view_host.h"
@@ skipping 39 matching lines @@
   value_ = value;
   if (native_wrapper_)
     native_wrapper_->SetValue(value);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Slider, View overrides:
 
 void Slider::Layout() {
   if (native_wrapper_) {
-    native_wrapper_->GetView()->SetBoundsRect(GetContentsBounds());
+    native_wrapper_->GetView()->SetBoundsRect(GetLocalBounds());
     native_wrapper_->GetView()->Layout();
   }
 }
 
 gfx::Size Slider::GetPreferredSize() {
   if (native_wrapper_)
     return native_wrapper_->GetPreferredSize();
   return gfx::Size();
 }
 
@@ skipping 36 matching lines @@
 NativeSliderWrapper* Slider::CreateWrapper() {
   NativeSliderWrapper* native_wrapper =
       NativeSliderWrapper::CreateWrapper(this);
 
   native_wrapper->UpdateEnabled();
 
   return native_wrapper;
 }
 
 }  // namespace views