Separate client surface reference tracking from FrameGenerator.

services/ui/ws/embedded_surface_tracker.cc

Index: services/ui/ws/embedded_surface_tracker.cc
diff --git a/services/ui/ws/embedded_surface_tracker.cc b/services/ui/ws/embedded_surface_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f3cb91e49d663be6d2edba609b7c43d5adc03d50
--- /dev/null
+++ b/services/ui/ws/embedded_surface_tracker.cc
@@ -0,0 +1,101 @@
+// 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.
+
+#include "services/ui/ws/embedded_surface_tracker.h"
+
+#include "base/logging.h"
+
+namespace ui {
+
+EmbeddedSurfaceTracker::EmbeddedSurfaceTracker() {}
+
+EmbeddedSurfaceTracker::~EmbeddedSurfaceTracker() {}
+
+void EmbeddedSurfaceTracker::SetCurrentSurfaceId(
+    const cc::SurfaceId& surface_id) {
+  DCHECK(surface_id.is_valid());
+
+  // The last submitted CompositorFrame for |current_surface_id_| still embeds
+  // the surfaces in |references_to_remove_| and hasn't embedded the surfaces in
+  // |references_to_add_| yet.
+  references_to_remove_.clear();
+  references_to_add_.clear();
+
+  current_surface_id_ = surface_id;
+
+  // Add references from updated |current_surface_id_| to all embedded surfaces.
+  for (auto& map_entry : embedded_surfaces_)
+    AddReference(current_surface_id_, map_entry.second);
+}
+
+void EmbeddedSurfaceTracker::EmbedSurface(const cc::SurfaceId& embedded_id) {
+  auto iter = embedded_surfaces_.find(embedded_id.frame_sink_id());
+
+  // This is the first surface for the FrameSinkId.
+  if (iter == embedded_surfaces_.end()) {
+    if (HasValidSurfaceId())
+      AddReference(current_surface_id_, embedded_id);
+
+    embedded_surfaces_[embedded_id.frame_sink_id()] = embedded_id;
+    return;
+  }
+
+  // This is not the first surface for the FrameSinkId, we are unembedding the
+  // old surface and embedding a new Surface.
+  cc::SurfaceId& stored_surface_id = iter->second;
+  DCHECK_NE(stored_surface_id, embedded_id);
+
+  if (HasValidSurfaceId()) {
+    RemoveReference(current_surface_id_, stored_surface_id);
+    AddReference(current_surface_id_, embedded_id);
+  }
+
+  stored_surface_id = embedded_id;
+}
+
+void EmbeddedSurfaceTracker::UnembedSurface(
+    const cc::FrameSinkId& frame_sink_id) {
+  auto iter = embedded_surfaces_.find(frame_sink_id);
+  if (iter == embedded_surfaces_.end())
+    return;
+
+  if (HasValidSurfaceId())
+    RemoveReference(current_surface_id_, iter->second);
+
+  embedded_surfaces_.erase(iter);
+}
+
+void EmbeddedSurfaceTracker::SendAddSurfaceReferences(
+    cc::mojom::MojoCompositorFrameSink* compositor_frame_sink) {
+  DCHECK(compositor_frame_sink);
+
+  if (references_to_add_.empty())
+    return;
+
+  compositor_frame_sink->AddSurfaceReferences(references_to_add_);
+  references_to_add_.clear();
+}
+
+void EmbeddedSurfaceTracker::SendRemoveSurfaceReferences(
+    cc::mojom::MojoCompositorFrameSink* compositor_frame_sink) {
+  DCHECK(compositor_frame_sink);
+
+  if (references_to_remove_.empty())
+    return;
+
+  compositor_frame_sink->RemoveSurfaceReferences(references_to_remove_);
+  references_to_remove_.clear();
+}
+
+void EmbeddedSurfaceTracker::AddReference(const cc::SurfaceId& parent_id,
+                                          const cc::SurfaceId& child_id) {
+  references_to_add_.push_back(cc::SurfaceReference(parent_id, child_id));
+}
+
+void EmbeddedSurfaceTracker::RemoveReference(const cc::SurfaceId& parent_id,
+                                             const cc::SurfaceId& child_id) {
+  references_to_remove_.push_back(cc::SurfaceReference(parent_id, child_id));
+}
+
+}  // namespace ui