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

components/html_viewer/web_theme_engine_impl.cc

Index: components/html_viewer/web_theme_engine_impl.cc
diff --git a/components/html_viewer/web_theme_engine_impl.cc b/components/html_viewer/web_theme_engine_impl.cc
index 21672a29cec34f952bffdb7c0ba04e90e7e02a06..15b06ae9ea15270ff7536faa60522b6f22e31168 100644
--- a/components/html_viewer/web_theme_engine_impl.cc
+++ b/components/html_viewer/web_theme_engine_impl.cc
@@ -167,9 +167,8 @@ void GetNativeThemeExtraParams(
 
 blink::WebSize WebThemeEngineImpl::getSize(WebThemeEngine::Part part) {
   ui::NativeTheme::ExtraParams extra;
-  return ui::NativeTheme::instance()->GetPartSize(NativeThemePart(part),
-                                                   ui::NativeTheme::kNormal,
-                                                   extra);
+  return ui::NativeTheme::GetInstanceForWeb()->GetPartSize(
+      NativeThemePart(part), ui::NativeTheme::kNormal, extra);
 }
 
 void WebThemeEngineImpl::paint(
@@ -181,11 +180,8 @@ 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);
 }
 
@@ -195,13 +191,9 @@ void WebThemeEngineImpl::paintStateTransition(blink::WebCanvas* canvas,
                                               WebThemeEngine::State endState,
                                               double progress,
                                               const blink::WebRect& rect) {
-  ui::NativeTheme::instance()->PaintStateTransition(
-      canvas,
-      NativeThemePart(part),
-      NativeThemeState(startState),
-      NativeThemeState(endState),
-      progress,
-      gfx::Rect(rect));
+  ui::NativeTheme::GetInstanceForWeb()->PaintStateTransition(
+      canvas, NativeThemePart(part), NativeThemeState(startState),
+      NativeThemeState(endState), progress, gfx::Rect(rect));
 }
 
 }  // namespace html_viewer