Use a struct for cc::Surface ids for more type safety

We currently represent surface ids as just an int, but may want to move
to a richer data structure in the future. Identifiers that are ints are also
pretty easy to confuse with other ints.

R=piman@chromium.org

Review URL: https://codereview.chromium.org/331533002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276923 0039d316-1c4b-4281-b951-d872f2087c98

23 files changed, 110 insertions, 66 deletions

diff --git a/cc/DEPS b/cc/DEPS
index d1fb990..33793d7 100644
--- a/cc/DEPS
+++ b/cc/DEPS
@@ -1,5 +1,4 @@
 include_rules = [
-  "-cc/surfaces", # cc shouldn't depend directly on the surface implementation
   "+gpu/GLES2",
   "+gpu/command_buffer/client/context_support.h",
   "+gpu/command_buffer/client/gles2_interface.h",
diff --git a/cc/cc.gyp b/cc/cc.gyp
index 7e33f42..6864e3a 100644
--- a/cc/cc.gyp
+++ b/cc/cc.gyp
@@ -494,6 +494,7 @@
         'surfaces/display_client.h',
         'surfaces/surface.cc',
         'surfaces/surface.h',
+        'surfaces/surface_id.h',
         'surfaces/surface_aggregator.cc',
         'surfaces/surface_aggregator.h',
         'surfaces/surface_client.h',
diff --git a/cc/layers/surface_layer.cc b/cc/layers/surface_layer.cc
index 385f158..f345b74 100644
--- a/cc/layers/surface_layer.cc
+++ b/cc/layers/surface_layer.cc
@@ -12,11 +12,12 @@ scoped_refptr<SurfaceLayer> SurfaceLayer::Create() {
   return make_scoped_refptr(new SurfaceLayer);
 }
 
-SurfaceLayer::SurfaceLayer() : Layer(), surface_id_(0) {}
+SurfaceLayer::SurfaceLayer() : Layer() {
+}
 
 SurfaceLayer::~SurfaceLayer() {}
 
-void SurfaceLayer::SetSurfaceId(int surface_id) {
+void SurfaceLayer::SetSurfaceId(SurfaceId surface_id) {
   surface_id_ = surface_id;
   SetNeedsPushProperties();
 }
@@ -26,7 +27,7 @@ scoped_ptr<LayerImpl> SurfaceLayer::CreateLayerImpl(LayerTreeImpl* tree_impl) {
 }
 
 bool SurfaceLayer::DrawsContent() const {
-  return surface_id_ && Layer::DrawsContent();
+  return !surface_id_.is_null() && Layer::DrawsContent();
 }
 
 void SurfaceLayer::PushPropertiesTo(LayerImpl* layer) {
diff --git a/cc/layers/surface_layer.h b/cc/layers/surface_layer.h
index 8ff3151..cf150ab 100644
--- a/cc/layers/surface_layer.h
+++ b/cc/layers/surface_layer.h
@@ -7,6 +7,7 @@
 
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer.h"
+#include "cc/surfaces/surface_id.h"
 
 namespace cc {
 
@@ -16,7 +17,7 @@ class CC_EXPORT SurfaceLayer : public Layer {
  public:
   static scoped_refptr<SurfaceLayer> Create();
 
-  void SetSurfaceId(int surface_id);
+  void SetSurfaceId(SurfaceId surface_id);
 
   // Layer overrides.
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
@@ -30,7 +31,7 @@ class CC_EXPORT SurfaceLayer : public Layer {
  private:
   virtual ~SurfaceLayer();
 
-  int surface_id_;
+  SurfaceId surface_id_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceLayer);
 };
diff --git a/cc/layers/surface_layer_impl.cc b/cc/layers/surface_layer_impl.cc
index 3bfae2d..6557e20 100644
--- a/cc/layers/surface_layer_impl.cc
+++ b/cc/layers/surface_layer_impl.cc
@@ -11,7 +11,8 @@
 namespace cc {
 
 SurfaceLayerImpl::SurfaceLayerImpl(LayerTreeImpl* tree_impl, int id)
-    : LayerImpl(tree_impl, id), surface_id_(0) {}
+    : LayerImpl(tree_impl, id) {
+}
 
 SurfaceLayerImpl::~SurfaceLayerImpl() {}
 
@@ -20,7 +21,7 @@ scoped_ptr<LayerImpl> SurfaceLayerImpl::CreateLayerImpl(
   return SurfaceLayerImpl::Create(tree_impl, id()).PassAs<LayerImpl>();
 }
 
-void SurfaceLayerImpl::SetSurfaceId(int surface_id) {
+void SurfaceLayerImpl::SetSurfaceId(SurfaceId surface_id) {
   if (surface_id_ == surface_id)
     return;
 
@@ -42,7 +43,7 @@ void SurfaceLayerImpl::AppendQuads(QuadSink* quad_sink,
 
   AppendDebugBorderQuad(quad_sink, shared_quad_state, append_quads_data);
 
-  if (!surface_id_)
+  if (surface_id_.is_null())
     return;
 
   scoped_ptr<SurfaceDrawQuad> quad = SurfaceDrawQuad::Create();
@@ -63,7 +64,7 @@ void SurfaceLayerImpl::GetDebugBorderProperties(SkColor* color,
 
 void SurfaceLayerImpl::AsValueInto(base::DictionaryValue* dict) const {
   LayerImpl::AsValueInto(dict);
-  dict->SetInteger("surface_id", surface_id_);
+  dict->SetInteger("surface_id", surface_id_.id);
 }
 
 const char* SurfaceLayerImpl::LayerTypeAsString() const {
diff --git a/cc/layers/surface_layer_impl.h b/cc/layers/surface_layer_impl.h
index b8447d0..82ac227 100644
--- a/cc/layers/surface_layer_impl.h
+++ b/cc/layers/surface_layer_impl.h
@@ -8,6 +8,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer_impl.h"
+#include "cc/surfaces/surface_id.h"
 
 namespace cc {
 
@@ -18,7 +19,7 @@ class CC_EXPORT SurfaceLayerImpl : public LayerImpl {
   }
   virtual ~SurfaceLayerImpl();
 
-  void SetSurfaceId(int surface_id);
+  void SetSurfaceId(SurfaceId surface_id);
 
   // LayerImpl overrides.
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
@@ -36,7 +37,7 @@ class CC_EXPORT SurfaceLayerImpl : public LayerImpl {
   virtual void AsValueInto(base::DictionaryValue* dict) const OVERRIDE;
   virtual const char* LayerTypeAsString() const OVERRIDE;
 
-  int surface_id_;
+  SurfaceId surface_id_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceLayerImpl);
 };
diff --git a/cc/layers/surface_layer_impl_unittest.cc b/cc/layers/surface_layer_impl_unittest.cc
index aeee4b6..fb0ed2f 100644
--- a/cc/layers/surface_layer_impl_unittest.cc
+++ b/cc/layers/surface_layer_impl_unittest.cc
@@ -21,7 +21,8 @@ TEST(SurfaceLayerImplTest, Occlusion) {
   surface_layer_impl->SetBounds(layer_size);
   surface_layer_impl->SetContentBounds(layer_size);
   surface_layer_impl->SetDrawsContent(true);
-  surface_layer_impl->SetSurfaceId(9);
+  SurfaceId surface_id(9);
+  surface_layer_impl->SetSurfaceId(surface_id);
 
   impl.CalcDrawProps(viewport_size);
 
diff --git a/cc/quads/draw_quad_unittest.cc b/cc/quads/draw_quad_unittest.cc
index c038214..7124db2 100644
--- a/cc/quads/draw_quad_unittest.cc
+++ b/cc/quads/draw_quad_unittest.cc
@@ -490,7 +490,7 @@ TEST(DrawQuadTest, CopyStreamVideoDrawQuad) {
 
 TEST(DrawQuadTest, CopySurfaceDrawQuad) {
   gfx::Rect visible_rect(40, 50, 30, 20);
-  int surface_id = 1234;
+  SurfaceId surface_id(1234);
   CREATE_SHARED_STATE();
 
   CREATE_QUAD_2_NEW(SurfaceDrawQuad, visible_rect, surface_id);
@@ -798,7 +798,7 @@ TEST_F(DrawQuadIteratorTest, StreamVideoDrawQuad) {
 
 TEST_F(DrawQuadIteratorTest, SurfaceDrawQuad) {
   gfx::Rect visible_rect(40, 50, 30, 20);
-  int surface_id = 4321;
+  SurfaceId surface_id(4321);
 
   CREATE_SHARED_STATE();
   CREATE_QUAD_2_NEW(SurfaceDrawQuad, visible_rect, surface_id);
diff --git a/cc/quads/surface_draw_quad.cc b/cc/quads/surface_draw_quad.cc
index e7d09d5..8591261c 100644
--- a/cc/quads/surface_draw_quad.cc
+++ b/cc/quads/surface_draw_quad.cc
@@ -9,7 +9,8 @@
 
 namespace cc {
 
-SurfaceDrawQuad::SurfaceDrawQuad() : surface_id(0) {}
+SurfaceDrawQuad::SurfaceDrawQuad() {
+}
 
 scoped_ptr<SurfaceDrawQuad> SurfaceDrawQuad::Create() {
   return make_scoped_ptr(new SurfaceDrawQuad);
@@ -18,7 +19,7 @@ scoped_ptr<SurfaceDrawQuad> SurfaceDrawQuad::Create() {
 void SurfaceDrawQuad::SetNew(const SharedQuadState* shared_quad_state,
                              const gfx::Rect& rect,
                              const gfx::Rect& visible_rect,
-                             int surface_id) {
+                             SurfaceId surface_id) {
   gfx::Rect opaque_rect;
   bool needs_blending = false;
   DrawQuad::SetAll(shared_quad_state, DrawQuad::SURFACE_CONTENT, rect,
@@ -31,7 +32,7 @@ void SurfaceDrawQuad::SetAll(const SharedQuadState* shared_quad_state,
                              const gfx::Rect& opaque_rect,
                              const gfx::Rect& visible_rect,
                              bool needs_blending,
-                             int surface_id) {
+                             SurfaceId surface_id) {
   DrawQuad::SetAll(shared_quad_state, DrawQuad::SURFACE_CONTENT, rect,
                    opaque_rect, visible_rect, needs_blending);
   this->surface_id = surface_id;
@@ -46,7 +47,7 @@ const SurfaceDrawQuad* SurfaceDrawQuad::MaterialCast(const DrawQuad* quad) {
 }
 
 void SurfaceDrawQuad::ExtendValue(base::DictionaryValue* value) const {
-  value->SetInteger("surface_id", surface_id);
+  value->SetInteger("surface_id", surface_id.id);
 }
 
 
diff --git a/cc/quads/surface_draw_quad.h b/cc/quads/surface_draw_quad.h
index f309211..e182ea3 100644
--- a/cc/quads/surface_draw_quad.h
+++ b/cc/quads/surface_draw_quad.h
@@ -8,6 +8,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/quads/draw_quad.h"
+#include "cc/surfaces/surface_id.h"
 
 namespace cc {
 
@@ -18,16 +19,16 @@ class CC_EXPORT SurfaceDrawQuad : public DrawQuad {
   void SetNew(const SharedQuadState* shared_quad_state,
               const gfx::Rect& rect,
               const gfx::Rect& visible_rect,
-              int surface_id);
+              SurfaceId surface_id);
 
   void SetAll(const SharedQuadState* shared_quad_state,
               const gfx::Rect& rect,
               const gfx::Rect& opaque_rect,
               const gfx::Rect& visible_rect,
               bool needs_blending,
-              int surface_id);
+              SurfaceId surface_id);
 
-  int surface_id;
+  SurfaceId surface_id;
 
   virtual void IterateResources(const ResourceIteratorCallback& callback)
       OVERRIDE;
diff --git a/cc/surfaces/display.cc b/cc/surfaces/display.cc
index 85d28b1..a39695f 100644
--- a/cc/surfaces/display.cc
+++ b/cc/surfaces/display.cc
@@ -153,8 +153,8 @@ bool Display::Draw() {
   return true;
 }
 
-int Display::CurrentSurfaceID() {
-  return current_surface_ ? current_surface_->surface_id() : 0;
+SurfaceId Display::CurrentSurfaceId() {
+  return current_surface_ ? current_surface_->surface_id() : SurfaceId();
 }
 
 void Display::ReturnResources(const ReturnedResourceArray& resources) {
diff --git a/cc/surfaces/display.h b/cc/surfaces/display.h
index 22bd074..85b172a 100644
--- a/cc/surfaces/display.h
+++ b/cc/surfaces/display.h
@@ -11,6 +11,7 @@
 #include "cc/output/renderer.h"
 #include "cc/surfaces/surface_aggregator.h"
 #include "cc/surfaces/surface_client.h"
+#include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
 namespace gfx {
@@ -39,7 +40,7 @@ class CC_SURFACES_EXPORT Display : public SurfaceClient,
   void Resize(const gfx::Size& new_size);
   bool Draw();
 
-  int CurrentSurfaceID();
+  SurfaceId CurrentSurfaceId();
 
   // OutputSurfaceClient implementation.
   virtual void DeferredInitialize() OVERRIDE {}
diff --git a/cc/surfaces/surface.cc b/cc/surfaces/surface.cc
index 82a1322..4012814 100644
--- a/cc/surfaces/surface.cc
+++ b/cc/surfaces/surface.cc
@@ -15,7 +15,7 @@ Surface::Surface(SurfaceManager* manager,
     : manager_(manager),
       client_(client),
       size_(size) {
-  surface_id_ = manager_->RegisterAndAllocateIDForSurface(this);
+  surface_id_ = manager_->RegisterAndAllocateIdForSurface(this);
 }
 
 Surface::~Surface() {
diff --git a/cc/surfaces/surface.h b/cc/surfaces/surface.h
index 8ed4399..60c992c 100644
--- a/cc/surfaces/surface.h
+++ b/cc/surfaces/surface.h
@@ -7,6 +7,7 @@
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 #include "ui/gfx/size.h"
 
@@ -23,7 +24,7 @@ class CC_SURFACES_EXPORT Surface {
   ~Surface();
 
   const gfx::Size& size() const { return size_; }
-  int surface_id() const { return surface_id_; }
+  SurfaceId surface_id() const { return surface_id_; }
 
   void QueueFrame(scoped_ptr<CompositorFrame> frame);
   // Returns the most recent frame that is eligible to be rendered.
@@ -33,7 +34,7 @@ class CC_SURFACES_EXPORT Surface {
   SurfaceManager* manager_;
   SurfaceClient* client_;
   gfx::Size size_;
-  int surface_id_;
+  SurfaceId surface_id_;
   // TODO(jamesr): Support multiple frames in flight.
   scoped_ptr<CompositorFrame> current_frame_;
 
diff --git a/cc/surfaces/surface_aggregator.cc b/cc/surfaces/surface_aggregator.cc
index 6b2178d..72300c0 100644
--- a/cc/surfaces/surface_aggregator.cc
+++ b/cc/surfaces/surface_aggregator.cc
@@ -24,9 +24,9 @@ SurfaceAggregator::SurfaceAggregator(SurfaceManager* manager)
 
 SurfaceAggregator::~SurfaceAggregator() {}
 
-DelegatedFrameData* SurfaceAggregator::GetReferencedDataForSurfaceID(
-    int surface_id) {
-  Surface* referenced_surface = manager_->GetSurfaceForID(surface_id);
+DelegatedFrameData* SurfaceAggregator::GetReferencedDataForSurfaceId(
+    SurfaceId surface_id) {
+  Surface* referenced_surface = manager_->GetSurfaceForId(surface_id);
   if (!referenced_surface)
     return NULL;  // Invalid surface id, skip this quad.
   CompositorFrame* referenced_frame = referenced_surface->GetEligibleFrame();
@@ -74,16 +74,16 @@ RenderPass::Id SurfaceAggregator::RemapPassId(
 
 void SurfaceAggregator::HandleSurfaceQuad(const SurfaceDrawQuad* surface_quad,
                                           RenderPass* dest_pass) {
-  int surface_id = surface_quad->surface_id;
+  SurfaceId surface_id = surface_quad->surface_id;
   // If this surface's id is already in our referenced set then it creates
   // a cycle in the graph and should be dropped.
-  if (referenced_surfaces_.count(surface_id))
+  if (referenced_surfaces_.count(surface_id.id))
     return;
   DelegatedFrameData* referenced_data =
-      GetReferencedDataForSurfaceID(surface_id);
+      GetReferencedDataForSurfaceId(surface_id);
   if (!referenced_data)
     return;
-  std::set<int>::iterator it = referenced_surfaces_.insert(surface_id).first;
+  std::set<int>::iterator it = referenced_surfaces_.insert(surface_id.id).first;
 
   const RenderPassList& referenced_passes = referenced_data->render_pass_list;
   for (size_t j = 0; j + 1 < referenced_passes.size(); ++j) {
@@ -91,7 +91,7 @@ void SurfaceAggregator::HandleSurfaceQuad(const SurfaceDrawQuad* surface_quad,
 
     scoped_ptr<RenderPass> copy_pass(RenderPass::Create());
 
-    RenderPass::Id remapped_pass_id = RemapPassId(source.id, surface_id);
+    RenderPass::Id remapped_pass_id = RemapPassId(source.id, surface_id.id);
 
     copy_pass->SetAll(remapped_pass_id,
                       source.output_rect,
@@ -111,7 +111,7 @@ void SurfaceAggregator::HandleSurfaceQuad(const SurfaceDrawQuad* surface_quad,
                     source.shared_quad_state_list,
                     gfx::Transform(),
                     copy_pass.get(),
-                    surface_id);
+                    surface_id.id);
 
     dest_pass_list_->push_back(copy_pass.Pass());
   }
@@ -125,7 +125,7 @@ void SurfaceAggregator::HandleSurfaceQuad(const SurfaceDrawQuad* surface_quad,
                   last_pass.shared_quad_state_list,
                   surface_quad->quadTransform(),
                   dest_pass,
-                  surface_id);
+                  surface_id.id);
 
   referenced_surfaces_.erase(it);
 }
@@ -215,8 +215,8 @@ void SurfaceAggregator::CopyPasses(const RenderPassList& source_pass_list,
   }
 }
 
-scoped_ptr<CompositorFrame> SurfaceAggregator::Aggregate(int surface_id) {
-  Surface* surface = manager_->GetSurfaceForID(surface_id);
+scoped_ptr<CompositorFrame> SurfaceAggregator::Aggregate(SurfaceId surface_id) {
+  Surface* surface = manager_->GetSurfaceForId(surface_id);
   if (!surface)
     return scoped_ptr<CompositorFrame>();
   CompositorFrame* root_surface_frame = surface->GetEligibleFrame();
@@ -231,10 +231,10 @@ scoped_ptr<CompositorFrame> SurfaceAggregator::Aggregate(int surface_id) {
   const RenderPassList& source_pass_list =
       root_surface_frame->delegated_frame_data->render_pass_list;
 
-  std::set<int>::iterator it = referenced_surfaces_.insert(surface_id).first;
+  std::set<int>::iterator it = referenced_surfaces_.insert(surface_id.id).first;
 
   dest_pass_list_ = &frame->delegated_frame_data->render_pass_list;
-  CopyPasses(source_pass_list, surface_id);
+  CopyPasses(source_pass_list, surface_id.id);
 
   referenced_surfaces_.erase(it);
   DCHECK(referenced_surfaces_.empty());
diff --git a/cc/surfaces/surface_aggregator.h b/cc/surfaces/surface_aggregator.h
index 4115bc3..fe52050 100644
--- a/cc/surfaces/surface_aggregator.h
+++ b/cc/surfaces/surface_aggregator.h
@@ -10,6 +10,7 @@
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/quads/render_pass.h"
+#include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
 namespace cc {
@@ -24,10 +25,10 @@ class CC_SURFACES_EXPORT SurfaceAggregator {
   explicit SurfaceAggregator(SurfaceManager* manager);
   ~SurfaceAggregator();
 
-  scoped_ptr<CompositorFrame> Aggregate(int surface_id);
+  scoped_ptr<CompositorFrame> Aggregate(SurfaceId surface_id);
 
  private:
-  DelegatedFrameData* GetReferencedDataForSurfaceID(int surface_id);
+  DelegatedFrameData* GetReferencedDataForSurfaceId(SurfaceId surface_id);
   RenderPass::Id RemapPassId(RenderPass::Id surface_local_pass_id,
                              int surface_id);
 
diff --git a/cc/surfaces/surface_aggregator_test_helpers.cc b/cc/surfaces/surface_aggregator_test_helpers.cc
index 51d1cb6..747f84a 100644
--- a/cc/surfaces/surface_aggregator_test_helpers.cc
+++ b/cc/surfaces/surface_aggregator_test_helpers.cc
@@ -24,7 +24,7 @@ namespace test {
 
 void AddTestSurfaceQuad(TestRenderPass* pass,
                         const gfx::Size& surface_size,
-                        int surface_id) {
+                        SurfaceId surface_id) {
   gfx::Transform content_to_target_transform;
   gfx::Size content_bounds = surface_size;
   gfx::Rect visible_content_rect = gfx::Rect(surface_size);
diff --git a/cc/surfaces/surface_aggregator_test_helpers.h b/cc/surfaces/surface_aggregator_test_helpers.h
index fd2c8d3..10c5659 100644
--- a/cc/surfaces/surface_aggregator_test_helpers.h
+++ b/cc/surfaces/surface_aggregator_test_helpers.h
@@ -7,6 +7,7 @@
 
 #include "cc/quads/draw_quad.h"
 #include "cc/quads/render_pass.h"
+#include "cc/surfaces/surface_id.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/size.h"
 
@@ -25,7 +26,7 @@ struct Quad {
     return quad;
   }
 
-  static Quad SurfaceQuad(int surface_id) {
+  static Quad SurfaceQuad(SurfaceId surface_id) {
     Quad quad;
     quad.material = DrawQuad::SURFACE_CONTENT;
     quad.surface_id = surface_id;
@@ -41,7 +42,7 @@ struct Quad {
 
   DrawQuad::Material material;
   // Set when material==DrawQuad::SURFACE_CONTENT.
-  int surface_id;
+  SurfaceId surface_id;
   // Set when material==DrawQuad::SOLID_COLOR.
   SkColor color;
   // Set when material==DrawQuad::RENDER_PASS.
@@ -50,7 +51,6 @@ struct Quad {
  private:
   Quad()
       : material(DrawQuad::INVALID),
-        surface_id(-1),
         color(SK_ColorWHITE),
         render_pass_id(-1, -1) {}
 };
diff --git a/cc/surfaces/surface_aggregator_unittest.cc b/cc/surfaces/surface_aggregator_unittest.cc
index 1809409..aa5cea0 100644
--- a/cc/surfaces/surface_aggregator_unittest.cc
+++ b/cc/surfaces/surface_aggregator_unittest.cc
@@ -19,7 +19,12 @@
 
 namespace cc {
 namespace {
-const int kInvalidSurfaceId = -1;
+
+SurfaceId InvalidSurfaceId() {
+  static SurfaceId invalid;
+  invalid.id = -1;
+  return invalid;
+}
 
 class SurfaceAggregatorTest : public testing::Test {
  public:
@@ -31,7 +36,7 @@ class SurfaceAggregatorTest : public testing::Test {
 };
 
 TEST_F(SurfaceAggregatorTest, InvalidSurfaceId) {
-  scoped_ptr<CompositorFrame> frame = aggregator_.Aggregate(kInvalidSurfaceId);
+  scoped_ptr<CompositorFrame> frame = aggregator_.Aggregate(InvalidSurfaceId());
   EXPECT_FALSE(frame);
 }
 
@@ -258,7 +263,7 @@ TEST_F(SurfaceAggregatorValidSurfaceTest, MultiPassSurfaceReference) {
 // be dropped.
 TEST_F(SurfaceAggregatorValidSurfaceTest, InvalidSurfaceReference) {
   test::Quad quads[] = {test::Quad::SolidColorQuad(SK_ColorGREEN),
-                        test::Quad::SurfaceQuad(kInvalidSurfaceId),
+                        test::Quad::SurfaceQuad(InvalidSurfaceId()),
                         test::Quad::SolidColorQuad(SK_ColorBLUE)};
   test::Pass passes[] = {test::Pass(quads, arraysize(quads))};
 
diff --git a/cc/surfaces/surface_id.h b/cc/surfaces/surface_id.h
new file mode 100644
index 0000000..aa9474d
--- /dev/null
+++ b/cc/surfaces/surface_id.h
@@ -0,0 +1,29 @@
+// Copyright 2014 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_SURFACE_ID_H_
+#define CC_SURFACES_SURFACE_ID_H_
+
+namespace cc {
+
+struct SurfaceId {
+  SurfaceId() : id(0) {}
+  explicit SurfaceId(int id) : id(id) {}
+
+  bool is_null() const { return id == 0; }
+
+  int id;
+};
+
+inline bool operator==(const SurfaceId& a, const SurfaceId& b) {
+  return a.id == b.id;
+}
+
+inline bool operator!=(const SurfaceId& a, const SurfaceId& b) {
+  return !(a == b);
+}
+
+}  // namespace cc
+
+#endif  // CC_SURFACES_SURFACE_ID_H_
diff --git a/cc/surfaces/surface_manager.cc b/cc/surfaces/surface_manager.cc
index 366fa81..b41aefc 100644
--- a/cc/surfaces/surface_manager.cc
+++ b/cc/surfaces/surface_manager.cc
@@ -14,21 +14,21 @@ SurfaceManager::SurfaceManager()
 
 SurfaceManager::~SurfaceManager() {}
 
-int SurfaceManager::RegisterAndAllocateIDForSurface(Surface* surface) {
+SurfaceId SurfaceManager::RegisterAndAllocateIdForSurface(Surface* surface) {
   DCHECK(surface);
   int surface_id = next_surface_id_++;
   surface_map_[surface_id] = surface;
-  return surface_id;
+  return SurfaceId(surface_id);
 }
 
-void SurfaceManager::DeregisterSurface(int surface_id) {
-  SurfaceMap::iterator it = surface_map_.find(surface_id);
+void SurfaceManager::DeregisterSurface(SurfaceId surface_id) {
+  SurfaceMap::iterator it = surface_map_.find(surface_id.id);
   DCHECK(it != surface_map_.end());
   surface_map_.erase(it);
 }
 
-Surface* SurfaceManager::GetSurfaceForID(int surface_id) {
-  SurfaceMap::iterator it = surface_map_.find(surface_id);
+Surface* SurfaceManager::GetSurfaceForId(SurfaceId surface_id) {
+  SurfaceMap::iterator it = surface_map_.find(surface_id.id);
   if (it == surface_map_.end())
     return NULL;
   return it->second;
diff --git a/cc/surfaces/surface_manager.h b/cc/surfaces/surface_manager.h
index fe12dbf..b14259d 100644
--- a/cc/surfaces/surface_manager.h
+++ b/cc/surfaces/surface_manager.h
@@ -7,23 +7,23 @@
 
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
+#include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
-namespace gfx { class Size; }
-
 namespace cc {
 class CompositorFrame;
 class Surface;
+class SurfaceClient;
 
 class CC_SURFACES_EXPORT SurfaceManager {
  public:
   SurfaceManager();
   ~SurfaceManager();
 
-  int RegisterAndAllocateIDForSurface(Surface* surface);
-  void DeregisterSurface(int surface_id);
+  SurfaceId RegisterAndAllocateIdForSurface(Surface* surface);
+  void DeregisterSurface(SurfaceId surface_id);
 
-  Surface* GetSurfaceForID(int surface_id);
+  Surface* GetSurfaceForId(SurfaceId surface_id);
 
  private:
   typedef base::hash_map<int, Surface*> SurfaceMap;
diff --git a/cc/surfaces/surface_unittest.cc b/cc/surfaces/surface_unittest.cc
index 7b18512..df41083 100644
--- a/cc/surfaces/surface_unittest.cc
+++ b/cc/surfaces/surface_unittest.cc
@@ -13,15 +13,15 @@ namespace {
 TEST(SurfaceTest, SurfaceLifetime) {
   SurfaceManager manager;
 
-  int surface_id = 0;
+  SurfaceId surface_id;
   {
     Surface surface(&manager, NULL, gfx::Size(5, 5));
     surface_id = surface.surface_id();
-    EXPECT_GT(surface_id, 0);
-    EXPECT_EQ(&surface, manager.GetSurfaceForID(surface_id));
+    EXPECT_TRUE(!surface_id.is_null());
+    EXPECT_EQ(&surface, manager.GetSurfaceForId(surface_id));
   }
 
-  EXPECT_EQ(NULL, manager.GetSurfaceForID(surface_id));
+  EXPECT_EQ(NULL, manager.GetSurfaceForId(surface_id));
 }
 
 }  // namespace