Update from chromium https://crrev.com/304586

cc/resources/raster_source.h

Index: cc/resources/raster_source.h
diff --git a/cc/resources/raster_source.h b/cc/resources/raster_source.h
index f7ea2716b03820c1fad25644617f7cf0061287f4..5f200dbf76e959f01b9047e86a2b23a727c42fc5 100644
--- a/cc/resources/raster_source.h
+++ b/cc/resources/raster_source.h
@@ -81,6 +81,9 @@ class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
   // during rasterization.
   virtual void SetShouldAttemptToUseDistanceFieldText() = 0;
 
+  virtual void SetBackgoundColor(SkColor background_color) = 0;
+  virtual void SetRequiresClear(bool requires_clear) = 0;
+
   // Return true iff this raster source would benefit from using distance
   // field text.
   virtual bool ShouldAttemptToUseDistanceFieldText() const = 0;
@@ -90,9 +93,6 @@ class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
   virtual void AsValueInto(base::debug::TracedValue* array) const = 0;
   virtual skia::RefPtr<SkPicture> GetFlattenedPicture() = 0;
 
-  // TODO(vmpstr): This should be a layer property.
-  virtual bool IsMask() const = 0;
-
  protected:
   friend class base::RefCountedThreadSafe<RasterSource>;