Add a compositing display item which replaces transparency display item

cc/resources/compositing_display_item.cc

Index: cc/resources/compositing_display_item.cc
diff --git a/cc/resources/compositing_display_item.cc b/cc/resources/compositing_display_item.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ed9cbc13a715bce3855655754a79452017774efe
--- /dev/null
+++ b/cc/resources/compositing_display_item.cc
@@ -0,0 +1,81 @@
+// Copyright 2015 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 "cc/resources/compositing_display_item.h"
+
+#include "base/strings/stringprintf.h"
+#include "base/trace_event/trace_event_argument.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkPaint.h"
+#include "third_party/skia/include/core/SkXfermode.h"
+#include "ui/gfx/skia_util.h"
+
+namespace cc {
+
+CompositingDisplayItem::CompositingDisplayItem(float opacity,
+                                               SkXfermode::Mode xfermode,
+                                               skia::RefPtr<SkColorFilter> cf)
+    : opacity_(opacity), xfermode_(xfermode), color_filter_(cf) {
+}
+
+CompositingDisplayItem::~CompositingDisplayItem() {
+}
+
+void CompositingDisplayItem::Raster(SkCanvas* canvas,
+                                    SkDrawPictureCallback* callback) const {
+  SkPaint paint;
+  paint.setXfermodeMode(xfermode_);
+  paint.setAlpha(opacity_ * 255);
+  paint.setColorFilter(color_filter_.get());
+  canvas->saveLayer(NULL, &paint);
+}
+
+bool CompositingDisplayItem::IsSuitableForGpuRasterization() const {
+  return true;
+}
+
+int CompositingDisplayItem::ApproximateOpCount() const {
+  return 1;
+}
+
+size_t CompositingDisplayItem::PictureMemoryUsage() const {
+  // TODO(pdr): Include color_filter's memory here.
+  return sizeof(float) + sizeof(SkXfermode::Mode);
+}
+
+void CompositingDisplayItem::AsValueInto(
+    base::trace_event::TracedValue* array) const {
+  array->AppendString(base::StringPrintf(
+      "CompositingDisplayItem opacity: %f, xfermode: %d", opacity_, xfermode_));
+}
+
+EndCompositingDisplayItem::EndCompositingDisplayItem() {
+}
+
+EndCompositingDisplayItem::~EndCompositingDisplayItem() {
+}
+
+void EndCompositingDisplayItem::Raster(SkCanvas* canvas,
+                                       SkDrawPictureCallback* callback) const {
+  canvas->restore();
+}
+
+bool EndCompositingDisplayItem::IsSuitableForGpuRasterization() const {
+  return true;
+}
+
+int EndCompositingDisplayItem::ApproximateOpCount() const {
+  return 0;
+}
+
+size_t EndCompositingDisplayItem::PictureMemoryUsage() const {
+  return 0;
+}
+
+void EndCompositingDisplayItem::AsValueInto(
+    base::trace_event::TracedValue* array) const {
+  array->AppendString("EndCompositingDisplayItem");
+}
+
+}  // namespace cc