Revert of cc: Make PaintedScrollbarLayer not use ContentsScalingLayer

cc/test/layer_test_common.cc

Index: cc/test/layer_test_common.cc
diff --git a/cc/test/layer_test_common.cc b/cc/test/layer_test_common.cc
index b6a0da6f6c9a605bdc096ce6c1922382db30898f..7e835b892a59a1fe372672fad0dddd2dec52e13d 100644
--- a/cc/test/layer_test_common.cc
+++ b/cc/test/layer_test_common.cc
@@ -75,17 +75,9 @@
 
   // Quads that are fully occluded on one axis only should be shrunken.
   for (const auto& quad : quads) {
+    DCHECK(quad->quadTransform().IsIdentityOrIntegerTranslation());
     gfx::Rect target_rect =
         MathUtil::MapEnclosingClippedRect(quad->quadTransform(), quad->rect);
-    if (!quad->quadTransform().IsIdentityOrIntegerTranslation()) {
-      DCHECK(quad->quadTransform().IsPositiveScaleOrTranslation())
-          << quad->quadTransform().ToString();
-      gfx::RectF target_rectf =
-          MathUtil::MapClippedRect(quad->quadTransform(), quad->rect);
-      // Scale transforms allowed, as long as the final transformed rect
-      // ends up on integer boundaries for ease of testing.
-      DCHECK_EQ(target_rectf.ToString(), gfx::RectF(target_rect).ToString());
-    }
     gfx::Rect target_visible_rect = MathUtil::MapEnclosingClippedRect(
         quad->quadTransform(), quad->visible_rect);