Allow CanvasSkia to bind to an existing SkCanvas.

views/native_theme_painter.cc

Index: views/native_theme_painter.cc
diff --git a/views/native_theme_painter.cc b/views/native_theme_painter.cc
index 71bb71b6184576d15a176741af96a70f23031c5b..584667b92077d5d7fee2ca91a4b15d4c3511452a 100644
--- a/views/native_theme_painter.cc
+++ b/views/native_theme_painter.cc
@@ -28,7 +28,6 @@ gfx::Size NativeThemePainter::GetPreferredSize() {
 void NativeThemePainter::Paint(int w, int h, gfx::Canvas* canvas) {
   const gfx::NativeTheme* native_theme = gfx::NativeTheme::instance();
   gfx::NativeTheme::Part part = delegate_->GetThemePart();
-  gfx::CanvasSkia* skia_canvas = canvas->AsCanvasSkia();
   gfx::Rect rect(0, 0, w, h);
 
   if (delegate_->GetThemeAnimation() != NULL &&
@@ -37,19 +36,20 @@ void NativeThemePainter::Paint(int w, int h, gfx::Canvas* canvas) {
     gfx::NativeTheme::ExtraParams prev_extra;
     gfx::NativeTheme::State prev_state =
         delegate_->GetBackgroundThemeState(&prev_extra);
-    native_theme->Paint(skia_canvas, part, prev_state, rect, prev_extra);
+    native_theme->Paint(
+        canvas->GetSkCanvas(), part, prev_state, rect, prev_extra);
 
     // Composite foreground state above it.
     gfx::NativeTheme::ExtraParams extra;
     gfx::NativeTheme::State state = delegate_->GetForegroundThemeState(&extra);
     int alpha = delegate_->GetThemeAnimation()->CurrentValueBetween(0, 255);
-    skia_canvas->SaveLayerAlpha(static_cast<uint8>(alpha));
-    native_theme->Paint(skia_canvas, part, state, rect, extra);
-    skia_canvas->Restore();
+    canvas->SaveLayerAlpha(static_cast<uint8>(alpha));
+    native_theme->Paint(canvas->GetSkCanvas(), part, state, rect, extra);
+    canvas->Restore();
   } else {
     gfx::NativeTheme::ExtraParams extra;
     gfx::NativeTheme::State state = delegate_->GetThemeState(&extra);
-    native_theme->Paint(skia_canvas, part, state, rect, extra);
+    native_theme->Paint(canvas->GetSkCanvas(), part, state, rect, extra);
   }
 }