Move ReferencedSurfaceTracker into GpuCompositorFrameSink.

cc/surfaces/referenced_surface_tracker.cc

Index: cc/surfaces/referenced_surface_tracker.cc
diff --git a/cc/surfaces/referenced_surface_tracker.cc b/cc/surfaces/referenced_surface_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b2ffd540e6f2f4b3e8b3ddf87763245abd2aa6f3
--- /dev/null
+++ b/cc/surfaces/referenced_surface_tracker.cc
@@ -0,0 +1,80 @@
+// 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 "cc/surfaces/referenced_surface_tracker.h"
+
+#include <utility>
+
+#include "base/logging.h"
+
+namespace cc {
+
+ReferencedSurfaceTracker::ReferencedSurfaceTracker(
+    const FrameSinkId& frame_sink_id)
+    : current_surface_id_(frame_sink_id, LocalFrameId()) {
+  DCHECK(current_surface_id_.frame_sink_id().is_valid());
+}
+
+ReferencedSurfaceTracker::~ReferencedSurfaceTracker() {}
+
+void ReferencedSurfaceTracker::UpdateReferences(
+    const LocalFrameId& local_frame_id,
+    const std::vector<SurfaceId>& referenced_surfaces) {
+  DCHECK(local_frame_id.is_valid());
+
+  // Clear references to add/remove from the last frame.
+  references_to_remove_.clear();
+  references_to_add_.clear();
+
+  // If |current_surface_id_| is changing then update |current_surface_id_|.
+  // Also clear |referenced_surfaces_| because we haven't added any references
+  // from the new SurfaceId yet.
+  if (current_surface_id_.local_frame_id() != local_frame_id) {
+    current_surface_id_ =
+        SurfaceId(current_surface_id_.frame_sink_id(), local_frame_id);
+    referenced_surfaces_.clear();
+  }
+
+  std::unordered_set<SurfaceId, SurfaceIdHash> referenced_surface_set(
+      referenced_surfaces.begin(), referenced_surfaces.end());
+  ProcessNewReferences(referenced_surface_set);
+}
+
+void ReferencedSurfaceTracker::ProcessNewReferences(
+    const std::unordered_set<SurfaceId, SurfaceIdHash>&
+        new_referenced_surfaces) {
+  // Removed references for each SurfaceId in |referenced_surfaces_| if they
+  // aren't referenced anymore. Removing from a set invalidates iterators, so
+  // create a new vector then remove everything in it.
+  std::vector<SurfaceId> not_referenced;
+  for (const SurfaceId& surface_id : referenced_surfaces_) {
+    if (new_referenced_surfaces.count(surface_id) == 0)
+      not_referenced.push_back(surface_id);
+  }
+  for (const SurfaceId& surface_id : not_referenced)
+    RemoveSurfaceReference(surface_id);
+
+  // Add references for each SurfaceId in |new_referenced_surfaces| if they
+  // aren't already referenced.
+  for (const SurfaceId& surface_id : new_referenced_surfaces) {
+    if (referenced_surfaces_.count(surface_id) == 0)
+      AddSurfaceReference(surface_id);
+  }
+}
+
+void ReferencedSurfaceTracker::AddSurfaceReference(
+    const SurfaceId& surface_id) {
+  references_to_add_.push_back(
+      SurfaceReference(current_surface_id_, surface_id));
+  referenced_surfaces_.insert(surface_id);
+}
+
+void ReferencedSurfaceTracker::RemoveSurfaceReference(
+    const SurfaceId& surface_id) {
+  references_to_remove_.push_back(
+      SurfaceReference(current_surface_id_, surface_id));
+  referenced_surfaces_.erase(surface_id);
+}
+
+}  // namespace cc