compositor-worker: Introduce WebCompositorMutableState

cc/blink/web_compositor_mutable_state_provider_impl.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_BLINK_WEB_COMPOSITOR_MUTABLE_STATE_PROVIDER_IMPL_H_
+#define CC_BLINK_WEB_COMPOSITOR_MUTABLE_STATE_PROVIDER_IMPL_H_
+
+#include "base/compiler_specific.h"
+#include "base/containers/hash_tables.h"
+#include "cc/blink/cc_blink_export.h"
+
+#include "third_party/WebKit/public/platform/WebCompositorMutableStateProvider.h"
+
+namespace cc {
+class LayerTreeImpl;
+struct LayerTreeMutation;
+typedef base::hash_map<uint64_t, LayerTreeMutation> LayerTreeMutationMap;

[esprehn, 2016/01/06 19:48:37]

why not just include the header? typedef of a complex type like this seems a bit
error prone.

[Ian Vollick, 2016/01/08 03:01:53]

Done.

+}  // namespace cc
+
+namespace cc_blink {
+
+class WebCompositorMutableStateProviderImpl
+    : public blink::WebCompositorMutableStateProvider {
+ public:
+  // TODO(vollick): after slimming paint v2, this will need to operate on
+  // property trees, not the layer tree impl.
+  //
+  // The LayerTreeImpl and the LayerTreeMutationMap are both owned by caller.
+  CC_BLINK_EXPORT WebCompositorMutableStateProviderImpl(
+      cc::LayerTreeImpl* state,
+      cc::LayerTreeMutationMap* mutations);
+
+  CC_BLINK_EXPORT ~WebCompositorMutableStateProviderImpl() override;
+
+  CC_BLINK_EXPORT blink::WebPassOwnPtr<blink::WebCompositorMutableState>
+  getMutableStateFor(uint64_t element_id) override WARN_UNUSED_RESULT;
+
+ private:
+  cc::LayerTreeImpl* state_;
+  cc::LayerTreeMutationMap* mutations_;
+};
+
+}  // namespace cc_blink
+
+#endif  // CC_BLINK_WEB_COMPOSITOR_MUTABLE_STATE_PROVIDER_IMPL_H_