Remove unused paintScrollbarThumb impl.

content/shell/renderer/test_runner/test_interfaces.h

Index: content/shell/renderer/test_runner/test_interfaces.h
diff --git a/content/shell/renderer/test_runner/test_interfaces.h b/content/shell/renderer/test_runner/test_interfaces.h
index 8c2b048a06430b5f98f6408336380aabb45943cc..4f96f5116efe3ecf6a7e30932541be7d52b1da1b 100644
--- a/content/shell/renderer/test_runner/test_interfaces.h
+++ b/content/shell/renderer/test_runner/test_interfaces.h
@@ -10,13 +10,8 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
-#include "third_party/WebKit/public/platform/WebNonCopyable.h"
-
-#if defined(OS_MACOSX)
-#include "content/shell/renderer/test_runner/mock_web_theme_engine_mac.h"
-#else
 #include "content/shell/renderer/test_runner/mock_web_theme_engine.h"
-#endif
+#include "third_party/WebKit/public/platform/WebNonCopyable.h"
 
 namespace blink {
 class WebFrame;
@@ -70,11 +65,7 @@ class TestInterfaces {
   WebTestProxyBase* proxy_;
 
   std::vector<WebTestProxyBase*> window_list_;
-#if defined(OS_MACOSX)
-  scoped_ptr<MockWebThemeEngineMac> theme_engine_;
-#else
   scoped_ptr<MockWebThemeEngine> theme_engine_;
-#endif
 
   DISALLOW_COPY_AND_ASSIGN(TestInterfaces);
 };