Separate client surface reference tracking from FrameGenerator.

services/ui/ws/embedded_surface_tracker.h

Index: services/ui/ws/embedded_surface_tracker.h
diff --git a/services/ui/ws/embedded_surface_tracker.h b/services/ui/ws/embedded_surface_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..24403f9fc58dea38006fa63036f45d6d36deebd5
--- /dev/null
+++ b/services/ui/ws/embedded_surface_tracker.h
@@ -0,0 +1,102 @@
+// 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 SERVICES_UI_WS_EMBEDDED_SURFACE_TRACKER_H_
+#define SERVICES_UI_WS_EMBEDDED_SURFACE_TRACKER_H_
+
+#include <unordered_map>
+#include <vector>
+
+#include "base/macros.h"
+#include "cc/ipc/mojo_compositor_frame_sink.mojom.h"
+#include "cc/surfaces/frame_sink_id.h"
+#include "cc/surfaces/surface_id.h"
+#include "cc/surfaces/surface_reference.h"
+
+namespace ui {
+
+namespace test {
+class EmbeddedSurfaceTrackerTest;
+}
+
+// Tracks surface references from a client surface to all surfaces embedded in
+// the client surface. Handles updating the references when the client surface
+// resizes.
+// TODO(kylechar): This class should move somewhere else, cc/surfaces maybe?
+class EmbeddedSurfaceTracker {

[Fady Samuel, 2017/01/05 19:36:19]

Can we move this to cc/surfaces.

[kylechar, 2017/01/06 17:58:40]

Done.

+ public:
+  EmbeddedSurfaceTracker();
+  ~EmbeddedSurfaceTracker();
+
+  const cc::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 cc::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.
+  void EmbedSurface(const cc::SurfaceId& embedded_id);
+
+  // Removes reference from |current_surface_id_| to latest embedded surface for
+  // |frame_sink_id|. Does not send IPC.
+  void UnembedSurface(const cc::FrameSinkId& frame_sink_id);
+
+  // Sends IPC to add references in |references_to_add_|. This should be called
+  // *before* the next CompositorFrame is submitted. Does nothing if there are
+  // no references to add.
+  void SendAddSurfaceReferences(
+      cc::mojom::MojoCompositorFrameSink* compositor_frame_sink);

[Fady Samuel, 2017/01/05 19:36:19]

Don't depend on mojo.

[kylechar, 2017/01/06 17:58:40]

Done.

+
+  // Sends IPC to remove all references in |references_to_remove_|. This should
+  // be called *after* the next CompositorFrame is submitted. Does nothing if
+  // there are no references to remove.
+  void SendRemoveSurfaceReferences(
+      cc::mojom::MojoCompositorFrameSink* compositor_frame_sink);
+
+ 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 cc::SurfaceId& parent_id,
+                    const cc::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 cc::SurfaceId& parent_id,
+                       const cc::SurfaceId& child_id);
+
+  // The SurfaceId of the client surface that is embedding other surfaces.
+  cc::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<cc::FrameSinkId, cc::SurfaceId, cc::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<cc::SurfaceReference> references_to_remove_;
+
+  // References that should be added before the next CompositorFrame is
+  // submitted.
+  std::vector<cc::SurfaceReference> references_to_add_;
+
+  DISALLOW_COPY_AND_ASSIGN(EmbeddedSurfaceTracker);
+};
+
+}  // namespace ui
+
+#endif  // SERVICES_UI_WS_EMBEDDED_SURFACE_TRACKER_H_