Aura overlay scrollbars adjust color for dark backgrounds

content/child/webthemeengine_impl_default.cc

Index: content/child/webthemeengine_impl_default.cc
diff --git a/content/child/webthemeengine_impl_default.cc b/content/child/webthemeengine_impl_default.cc
index 7fa4ba7d6497c2d374257db255e91d283d2c24cc..5332f05f83b9dc01630868d6473809cbd0f7db12 100644
--- a/content/child/webthemeengine_impl_default.cc
+++ b/content/child/webthemeengine_impl_default.cc
@@ -8,7 +8,6 @@
 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/platform/WebRect.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
-#include "ui/native_theme/native_theme.h"
 
 using blink::WebCanvas;
 using blink::WebColor;
@@ -177,6 +176,17 @@ static void GetNativeThemeExtraParams(
       native_theme_extra_params->progress_bar.value_rect_height =
           extra_params->progressBar.valueRectHeight;
       break;
+    case WebThemeEngine::PartScrollbarHorizontalThumb:
+    case WebThemeEngine::PartScrollbarVerticalThumb:
+      if (extra_params) {
+        native_theme_extra_params->scrollbar_theme =

[bokan, 2016/10/21 16:57:14]

These should be |native_theme_extra_params->scrollbar_thumb.scrollbar_theme|.
See my comment in native_theme.h.

+            static_cast<ui::NativeTheme::ScrollbarOverlayColorTheme>(
+                extra_params->scrollbarTheme);
+      } else {

[bokan, 2016/10/21 16:57:14]

The other cases here assume extra_params is always given, seems we can assume
that too.

+        native_theme_extra_params->scrollbar_theme = ui::NativeTheme::
+            ScrollbarOverlayColorTheme::ScrollbarOverlayColorThemeDefault;
+      }
+      break;
     default:
       break;  // Parts that have no extra params get here.
   }
@@ -221,15 +231,17 @@ void WebThemeEngineImpl::paint(
       native_theme_extra_params);
 }
 
-void WebThemeEngineImpl::paintStateTransition(blink::WebCanvas* canvas,
-                                              WebThemeEngine::Part part,
-                                              WebThemeEngine::State startState,
-                                              WebThemeEngine::State endState,
-                                              double progress,
-                                              const blink::WebRect& rect) {
+void WebThemeEngineImpl::paintStateTransition(
+    blink::WebCanvas* canvas,
+    WebThemeEngine::Part part,
+    WebThemeEngine::State startState,
+    WebThemeEngine::State endState,
+    double progress,
+    const blink::WebRect& rect,
+    ui::NativeTheme::ScrollbarOverlayColorTheme theme) {
   ui::NativeTheme::GetInstanceForWeb()->PaintStateTransition(
       canvas, NativeThemePart(part), NativeThemeState(startState),
-      NativeThemeState(endState), progress, gfx::Rect(rect));
+      NativeThemeState(endState), progress, gfx::Rect(rect), theme);
 }
 
 #if defined(OS_WIN)