WIP: Propagate SurfaceID up window tree hierarchy

cc/surfaces/surface_sequence_generator.cc

Index: cc/surfaces/surface_sequence_generator.cc
diff --git a/cc/trees/surface_sequence_generator.cc b/cc/surfaces/surface_sequence_generator.cc
similarity index 70%
rename from cc/trees/surface_sequence_generator.cc
rename to cc/surfaces/surface_sequence_generator.cc
index f2196892519bbe57661b6c78fed8570fcd2d8215..8119a137cf565b057442a4fc522a1ad9811f70c8 100644
--- a/cc/trees/surface_sequence_generator.cc
+++ b/cc/surfaces/surface_sequence_generator.cc
@@ -2,18 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <cc/trees/surface_sequence_generator.h>
+#include "cc/surfaces/surface_sequence_generator.h"
+
 #include "cc/surfaces/surface_sequence.h"
 
 namespace cc {
 
 SurfaceSequenceGenerator::SurfaceSequenceGenerator()
-    : surface_client_id_(0u), next_surface_sequence_(1u) {}
+    : next_surface_sequence_(1u) {}
 
 SurfaceSequenceGenerator::~SurfaceSequenceGenerator() = default;
 
 SurfaceSequence SurfaceSequenceGenerator::CreateSurfaceSequence() {
-  return SurfaceSequence(surface_client_id_, next_surface_sequence_++);
+  return SurfaceSequence(frame_sink_id_, next_surface_sequence_++);
 }
 
 }  // namespace cc