Change name of NativeTheme::instance() to make it clear it's web only.

content/child/webthemeengine_impl_android.cc

Index: content/child/webthemeengine_impl_android.cc
diff --git a/content/child/webthemeengine_impl_android.cc b/content/child/webthemeengine_impl_android.cc
index eafe8a4239f9203c757167abcf2a57b97294f5ca..83db469f04717d7f899cc1ae2613c31bdedf795f 100644
--- a/content/child/webthemeengine_impl_android.cc
+++ b/content/child/webthemeengine_impl_android.cc
@@ -159,7 +159,7 @@ static void GetNativeThemeExtraParams(
 
 blink::WebSize WebThemeEngineImpl::getSize(WebThemeEngine::Part part) {
   ui::NativeTheme::ExtraParams extra;
-  return ui::NativeTheme::instance()->GetPartSize(
+  return ui::NativeTheme::GetInstanceForWeb()->GetPartSize(
       NativeThemePart(part), ui::NativeTheme::kNormal, extra);
 }
 
@@ -172,11 +172,8 @@ void WebThemeEngineImpl::paint(
   ui::NativeTheme::ExtraParams native_theme_extra_params;
   GetNativeThemeExtraParams(
       part, state, extra_params, &native_theme_extra_params);
-  ui::NativeTheme::instance()->Paint(
-      canvas,
-      NativeThemePart(part),
-      NativeThemeState(state),
-      gfx::Rect(rect),
+  ui::NativeTheme::GetInstanceForWeb()->Paint(
+      canvas, NativeThemePart(part), NativeThemeState(state), gfx::Rect(rect),
       native_theme_extra_params);
 }
 }  // namespace content