compositor-worker: Introduce WebCompositorMutableState

cc/animation/layer_tree_mutation.h

+// 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.
+
+#ifndef CC_ANIMATION_LAYER_TREE_MUTATION_H_
+#define CC_ANIMATION_LAYER_TREE_MUTATION_H_
+
+#include "base/containers/hash_tables.h"
+#include "cc/animation/mutable_properties.h"
+#include "third_party/skia/include/utils/SkMatrix44.h"
+
+namespace cc {
+
+class LayerTreeMutation {
+ public:
+  void SetOpacity(float opacity) {
+    mutated_flags_ |= kMutablePropertyOpacity;
+    opacity_ = opacity;
+  }
+  void SetScrollLeft(float scroll_left) {
+    mutated_flags_ |= kMutablePropertyScrollLeft;
+    scroll_left_ = scroll_left;
+  }
+  void SetScrollTop(float scroll_top) {
+    mutated_flags_ |= kMutablePropertyScrollTop;
+    scroll_top_ = scroll_top;
+  }
+  void SetTransform(const SkMatrix44& transform) {
+    mutated_flags_ |= kMutablePropertyTransform;
+    transform_ = transform;
+  }
+
+  bool is_opacity_mutated() const {
+    return !!(mutated_flags_ & kMutablePropertyOpacity);
+  }
+  bool is_scroll_left_mutated() const {
+    return !!(mutated_flags_ & kMutablePropertyScrollLeft);
+  }
+  bool is_scroll_top_mutated() const {
+    return !!(mutated_flags_ & kMutablePropertyScrollTop);
+  }
+  bool is_transform_mutated() const {
+    return !!(mutated_flags_ & kMutablePropertyTransform);
+  }
+
+  float opacity() const { return opacity_; }
+  float scroll_left() const { return scroll_left_; }
+  float scroll_top() const { return scroll_top_; }
+  SkMatrix44 transform() const { return transform_; }
+
+ private:
+  uint32_t mutated_flags_ = 0;
+  float opacity_ = 0;
+  float scroll_left_ = 0;
+  float scroll_top_ = 0;
+  SkMatrix44 transform_;
+};
+
+typedef base::hash_map<uint64_t, LayerTreeMutation> LayerTreeMutationMap;
+
+}  // namespace cc
+
+#endif  // CC_ANIMATION_LAYER_TREE_MUTATION_H_