Split NativeThemeAura into Overlay and NonOverlay versions.

content/child/webthemeengine_impl_default.cc

 // Copyright 2014 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 "content/child/webthemeengine_impl_default.h"
 
 #include "build/build_config.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/platform/WebRect.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
+#include "third_party/WebKit/public/web/WebRuntimeFeatures.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/native_theme/overlay_scrollbar_constants_aura.h"
 
 using blink::WebCanvas;
 using blink::WebColor;
 using blink::WebRect;
 using blink::WebThemeEngine;
 using blink::WebScrollbarOverlayColorTheme;
 
 namespace content {
 namespace {
 
 #if defined(OS_WIN)
 // The width of a vertical scroll bar in dips.
 int32_t g_vertical_scroll_bar_width;
 
 // The height of a horizontal scroll bar in dips.
 int32_t g_horizontal_scroll_bar_height;
 
 // The height of the arrow bitmap on a vertical scroll bar in dips.
 int32_t g_vertical_arrow_bitmap_height;
 
 // The width of the arrow bitmap on a horizontal scroll bar in dips.
 int32_t g_horizontal_arrow_bitmap_width;
 #endif
 
+ui::NativeTheme* nativeThemeInstance() {
+  return ui::NativeTheme::GetInstanceForWeb(
+      blink::WebRuntimeFeatures::isOverlayScrollbarsEnabled());
+}
+
 }  // namespace
 
 static ui::NativeTheme::Part NativeThemePart(
     WebThemeEngine::Part part) {
   switch (part) {
     case WebThemeEngine::PartScrollbarDownArrow:
       return ui::NativeTheme::kScrollbarDownArrow;
     case WebThemeEngine::PartScrollbarLeftArrow:
       return ui::NativeTheme::kScrollbarLeftArrow;
     case WebThemeEngine::PartScrollbarRightArrow:
@@ skipping 172 matching lines @@
     case ui::NativeTheme::kScrollbarHorizontalTrack:
     case ui::NativeTheme::kScrollbarVerticalTrack: {
       return gfx::Size(g_vertical_scroll_bar_width,
                        g_vertical_scroll_bar_width);
     }
 
     default:
       break;
   }
 #endif
-  return ui::NativeTheme::GetInstanceForWeb()->GetPartSize(
+  return nativeThemeInstance()->GetPartSize(
       native_theme_part, ui::NativeTheme::kNormal, extra);
 }
 
 void WebThemeEngineImpl::paint(
     blink::WebCanvas* canvas,
     WebThemeEngine::Part part,
     WebThemeEngine::State state,
     const blink::WebRect& rect,
     const WebThemeEngine::ExtraParams* extra_params) {
   ui::NativeTheme::ExtraParams native_theme_extra_params;
   GetNativeThemeExtraParams(
       part, state, extra_params, &native_theme_extra_params);
-  ui::NativeTheme::GetInstanceForWeb()->Paint(
+  nativeThemeInstance()->Paint(
       canvas, NativeThemePart(part), NativeThemeState(state), gfx::Rect(rect),
       native_theme_extra_params);
 }
 
 void WebThemeEngineImpl::getOverlayScrollbarStyle(ScrollbarStyle* style) {
   style->fadeOutDelaySeconds = ui::kOverlayScrollbarFadeOutDelay.InSecondsF();
   style->fadeOutDurationSeconds =
       ui::kOverlayScrollbarFadeOutDuration.InSecondsF();
   // The other fields in this struct are used only on Android to draw solid
   // color scrollbars. On other platforms the scrollbars are painted in
   // NativeTheme so these fields are unused.
 }
 
 #if defined(OS_WIN)
 // static
 void WebThemeEngineImpl::cacheScrollBarMetrics(
     int32_t vertical_scroll_bar_width,
     int32_t horizontal_scroll_bar_height,
     int32_t vertical_arrow_bitmap_height,
     int32_t horizontal_arrow_bitmap_width) {
   g_vertical_scroll_bar_width = vertical_scroll_bar_width;
   g_horizontal_scroll_bar_height = horizontal_scroll_bar_height;
   g_vertical_arrow_bitmap_height = vertical_arrow_bitmap_height;
   g_horizontal_arrow_bitmap_width = horizontal_arrow_bitmap_width;
 }
 #endif
 
 }  // namespace content