Separate client surface reference tracking from FrameGenerator.

cc/surfaces/embedded_surface_tracker.h

Index: cc/surfaces/embedded_surface_tracker.h
diff --git a/cc/surfaces/embedded_surface_tracker.h b/cc/surfaces/embedded_surface_tracker.h
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index 0000000000000000000000000000000000000000..858d04c9779456849fb3f925ee153cf181f2a168
--- /dev/null
+++ b/cc/surfaces/embedded_surface_tracker.h
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+// Copyright 2016 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_SURFACES_EMBEDDED_SURFACE_TRACKER_H_
+#define CC_SURFACES_EMBEDDED_SURFACE_TRACKER_H_
+
+#include <unordered_map>
+#include <vector>
+
+#include "base/macros.h"
+#include "cc/surfaces/frame_sink_id.h"
+#include "cc/surfaces/surface_id.h"
+#include "cc/surfaces/surface_reference.h"
+#include "cc/surfaces/surfaces_export.h"
+
+namespace cc {
+
+namespace test {
+class EmbeddedSurfaceTrackerTest;
+}
+
+// Tracks surface references from a client surface to embedded surfaces. Handles
+// updating the references when the client surface resizes.
+class CC_SURFACES_EXPORT EmbeddedSurfaceTracker {
+ public:
+  EmbeddedSurfaceTracker();
+  ~EmbeddedSurfaceTracker();
+
+  const SurfaceId& current_surface_id() const { return current_surface_id_; }
+
+  // Checks if the client has a valid SurfaceId. This will become true after
+  // SetCurrentSurfaceId() is called for the first time. No references will be
+  // added or removed until this is true.
+  bool HasValidSurfaceId() const { return current_surface_id_.is_valid(); }
+
+  // Sets |current_surface_id_| when the client switches surfaces. Clears all
+  // references waiting to be added or removed, since no CompositorFrame will be
+  // submitted for the previous surface now. Generates new references from the
+  // new surface to all embedded surfaces. Does not send IPC.
+  void SetCurrentSurfaceId(const SurfaceId& surface_id);
+
+  // Adds a reference from |current_surface_id_| to |embedded_id| and records
+  // |embedded_id|. If an existing surface with the same FrameSinkId is embedded
+  // removes the reference to it. Does not send IPC. Returns true for the first
+  // surface from a FrameSinkId and false for all subsequent surfaces.
+  bool EmbedSurface(const SurfaceId& embedded_id);
+
+  // Removes reference from |current_surface_id_| to latest embedded surface for
+  // |frame_sink_id|. Does not send IPC.
+  void UnembedSurface(const FrameSinkId& frame_sink_id);
+
+  // Returns |references_to_add_| and clears contents. It's expected this will
+  // be called immediately before submitting a CompositorFrame and caller will
+  // add references via IPC.
+  std::vector<SurfaceReference> GetReferencesToAdd();
+  bool HasReferencesToAdd() const { return !references_to_add_.empty(); }
+
+  // Returns |references_to_remove_| and clears contents. It's expected this
+  // will be called immediately after submitting a CompositorFrame and caller
+  // will remove references via IPC.
+  std::vector<SurfaceReference> GetReferencesToRemove();
+  bool HasReferencesToRemove() const { return !references_to_remove_.empty(); }
+
+ private:
+  friend class test::EmbeddedSurfaceTrackerTest;
+
+  // Records adding a reference from |parent_id| to |child_id|. References are
+  // not actually added until SendAddSurfaceReferences() is called.
+  void AddReference(const SurfaceId& parent_id, const SurfaceId& child_id);
+
+  // Records removing a reference from |parent_id| to |child_id|. References
+  // are not actually removed until SendRemoveSurfaceReferences() is called.
+  void RemoveReference(const SurfaceId& parent_id, const SurfaceId& child_id);
+
+  // The id of the client surface that is embedding other surfaces.
+  SurfaceId current_surface_id_;
+
+  // Surfaces that are embedded by the client surface. A reference from
+  // |current_surface_id_| will be added if it's valid.
+  std::unordered_map<FrameSinkId, SurfaceId, FrameSinkIdHash>
+      embedded_surfaces_;
+
+  // References to surfaces that should be removed after the next
+  // CompositorFrame has been submitted and the surfaces are no longer embedded.
+  std::vector<SurfaceReference> references_to_remove_;
+
+  // References that should be added before the next CompositorFrame is
+  // submitted.
+  std::vector<SurfaceReference> references_to_add_;
+
+  DISALLOW_COPY_AND_ASSIGN(EmbeddedSurfaceTracker);
+};
+
+}  // namespace cc
+
+#endif  // CC_SURFACES_EMBEDDED_SURFACE_TRACKER_H_