Add SurfaceReference class.

Add a simple class SurfaceReference that holds a parent and child
SurfaceId. Also add Mojo struct and StructTraits for use over IPC.

Update SurfaceId and LocalFrameId struct traits slightly to avoid
unnecessary copies. This requires a friend declaration but it seems
reasonable and is done elsewhere.

BUG=659227
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2537343004
Cr-Commit-Position: refs/heads/master@{#436423}

cc/ipc/BUILD.gn

@@ -54,6 +54,7 @@ mojom("interfaces") {
     "selection.mojom",
     "shared_quad_state.mojom",
     "surface_id.mojom",
+    "surface_reference.mojom",
     "surface_sequence.mojom",
     "transferable_resource.mojom",
   ]
@@ -111,6 +112,7 @@ cc_source_set("struct_traits") {
     "selection_struct_traits.h",
     "shared_quad_state_struct_traits.h",
     "surface_id_struct_traits.h",
+    "surface_reference_struct_traits.h",
     "surface_sequence_struct_traits.h",
     "transferable_resource_struct_traits.cc",
     "transferable_resource_struct_traits.h",

cc/ipc/local_frame_id_struct_traits.h

@@ -24,12 +24,8 @@ struct StructTraits<cc::mojom::LocalFrameIdDataView, cc::LocalFrameId> {
 
   static bool Read(cc::mojom::LocalFrameIdDataView data,
                    cc::LocalFrameId* out) {
-    base::UnguessableToken nonce;
-    if (!data.ReadNonce(&nonce))
-      return false;
-
-    *out = cc::LocalFrameId(data.local_id(), nonce);
-    return true;
+    out->local_id_ = data.local_id();
+    return data.ReadNonce(&out->nonce_);
   }
 };
 

cc/ipc/struct_traits_unittest.cc

@@ -95,6 +95,12 @@ class StructTraitsTest : public testing::Test, public mojom::TraitsTestService {
     callback.Run(s);
   }
 
+  void EchoSurfaceReference(
+      const SurfaceReference& s,
+      const EchoSurfaceReferenceCallback& callback) override {
+    callback.Run(s);
+  }
+
   void EchoSurfaceSequence(
       const SurfaceSequence& s,
       const EchoSurfaceSequenceCallback& callback) override {
@@ -779,6 +785,22 @@ TEST_F(StructTraitsTest, SurfaceId) {
   EXPECT_EQ(local_frame_id, output.local_frame_id());
 }
 
+TEST_F(StructTraitsTest, SurfaceReference) {
+  const SurfaceId parent_id(
+      FrameSinkId(2016, 1234),
+      LocalFrameId(0xfbadbeef, base::UnguessableToken::Deserialize(123, 456)));
+  const SurfaceId child_id(
+      FrameSinkId(1111, 9999),
+      LocalFrameId(0xabcdabcd, base::UnguessableToken::Deserialize(333, 333)));
+  const SurfaceReference input(parent_id, child_id);
+
+  mojom::TraitsTestServicePtr proxy = GetTraitsTestProxy();
+  SurfaceReference output;
+  proxy->EchoSurfaceReference(input, &output);
+  EXPECT_EQ(parent_id, output.parent_id());
+  EXPECT_EQ(child_id, output.child_id());
+}
+
 TEST_F(StructTraitsTest, SurfaceSequence) {
   const FrameSinkId frame_sink_id(2016, 1234);
   const uint32_t sequence = 0xfbadbeef;

cc/ipc/surface_id_struct_traits.h

@@ -9,6 +9,7 @@
 #include "cc/ipc/local_frame_id_struct_traits.h"
 #include "cc/ipc/surface_id.mojom-shared.h"
 #include "cc/surfaces/frame_sink_id.h"
+#include "cc/surfaces/local_frame_id.h"
 #include "cc/surfaces/surface_id.h"
 
 namespace mojo {
@@ -24,16 +25,8 @@ struct StructTraits<cc::mojom::SurfaceIdDataView, cc::SurfaceId> {
   }
 
   static bool Read(cc::mojom::SurfaceIdDataView data, cc::SurfaceId* out) {
-    cc::FrameSinkId frame_sink_id;
-    if (!data.ReadFrameSinkId(&frame_sink_id))
-      return false;
-
-    cc::LocalFrameId local_frame_id;
-    if (!data.ReadLocalFrameId(&local_frame_id))
-      return false;
-
-    *out = cc::SurfaceId(frame_sink_id, local_frame_id);
-    return true;
+    return data.ReadFrameSinkId(&out->frame_sink_id_) &&
+           data.ReadLocalFrameId(&out->local_frame_id_);
   }
 };
 

cc/ipc/surface_reference.mojom

@@ -0,0 +1,12 @@
+// 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.
+
+module cc.mojom;
+
+import "cc/ipc/surface_id.mojom";
+
+struct SurfaceReference {
+  SurfaceId parent_id;
+  SurfaceId child_id;
+};

cc/ipc/surface_reference.typemap

@@ -0,0 +1,11 @@
+# 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.
+
+mojom = "//cc/ipc/surface_reference.mojom"
+public_headers = [ "//cc/surfaces/surface_reference.h" ]
+traits_headers = [ "//cc/ipc/surface_reference_struct_traits.h" ]
+deps = [
+  "//cc/ipc:struct_traits",
+]
+type_mappings = [ "cc.mojom.SurfaceReference=cc::SurfaceReference" ]

cc/ipc/surface_reference_struct_traits.h

@@ -0,0 +1,34 @@
+// 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 CC_IPC_SURFACE_REFERENCE_STRUCT_TRAITS_H_
+#define CC_IPC_SURFACE_REFERENCE_STRUCT_TRAITS_H_
+
+#include "cc/ipc/surface_id_struct_traits.h"
+#include "cc/ipc/surface_reference.mojom-shared.h"
+#include "cc/surfaces/surface_id.h"
+#include "cc/surfaces/surface_reference.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<cc::mojom::SurfaceReferenceDataView, cc::SurfaceReference> {
+  static const cc::SurfaceId& parent_id(const cc::SurfaceReference& ref) {
+    return ref.parent_id();
+  }
+
+  static const cc::SurfaceId& child_id(const cc::SurfaceReference& ref) {
+    return ref.child_id();
+  }
+
+  static bool Read(cc::mojom::SurfaceReferenceDataView data,
+                   cc::SurfaceReference* out) {
+    return data.ReadParentId(&out->parent_id_) &&
+           data.ReadChildId(&out->child_id_);
+  }
+};
+
+}  // namespace mojo
+
+#endif  // CC_IPC_SURFACE_REFERENCE_STRUCT_TRAITS_H_

cc/ipc/traits_test_service.mojom

@@ -16,6 +16,7 @@ import "cc/ipc/returned_resource.mojom";
 import "cc/ipc/selection.mojom";
 import "cc/ipc/shared_quad_state.mojom";
 import "cc/ipc/surface_id.mojom";
+import "cc/ipc/surface_reference.mojom";
 import "cc/ipc/surface_sequence.mojom";
 import "cc/ipc/transferable_resource.mojom";
 
@@ -56,6 +57,9 @@ interface TraitsTestService {
   [Sync]
   EchoSurfaceId(SurfaceId s) => (SurfaceId pass);
 
+  [Sync]
+  EchoSurfaceReference(SurfaceReference r) => (SurfaceReference pass);
+
   [Sync]
   EchoSurfaceSequence(SurfaceSequence s) => (SurfaceSequence pass);
 

cc/ipc/typemaps.gni

@@ -16,6 +16,7 @@ typemaps = [
   "//cc/ipc/selection.typemap",
   "//cc/ipc/shared_quad_state.typemap",
   "//cc/ipc/surface_id.typemap",
+  "//cc/ipc/surface_reference.typemap",
   "//cc/ipc/surface_sequence.typemap",
   "//cc/ipc/transferable_resource.typemap",
 ]

cc/surfaces/BUILD.gn

@@ -12,13 +12,16 @@ cc_source_set("surface_id") {
     "local_frame_id.h",
     "surface_id.cc",
     "surface_id.h",
+    "surface_reference.cc",
+    "surface_reference.h",
     "surface_sequence.h",
     "surface_sequence_generator.cc",
     "surface_sequence_generator.h",
   ]
 
   deps = [
     "//base",
+    "//mojo/public/cpp/bindings:struct_traits",
   ]
 }
 

cc/surfaces/DEPS

@@ -0,0 +1,3 @@
+include_rules = [
+  "+mojo/public/cpp/bindings/struct_traits.h",
+]

cc/surfaces/local_frame_id.h

@@ -13,8 +13,12 @@
 
 #include "base/hash.h"
 #include "base/unguessable_token.h"
+#include "mojo/public/cpp/bindings/struct_traits.h"
 
 namespace cc {
+namespace mojom {
+class LocalFrameIdDataView;
+}
 
 class LocalFrameId {
  public:
@@ -53,6 +57,8 @@ class LocalFrameId {
   std::string ToString() const;
 
  private:
+  friend struct mojo::StructTraits<mojom::LocalFrameIdDataView, LocalFrameId>;
+
   uint32_t local_id_;
   base::UnguessableToken nonce_;
 };

cc/surfaces/surface_id.h

@@ -14,8 +14,12 @@
 #include "base/hash.h"
 #include "cc/surfaces/frame_sink_id.h"
 #include "cc/surfaces/local_frame_id.h"
+#include "mojo/public/cpp/bindings/struct_traits.h"
 
 namespace cc {
+namespace mojom {
+class SurfaceIdDataView;
+}
 
 class SurfaceId {
  public:
@@ -62,6 +66,8 @@ class SurfaceId {
   }
 
  private:
+  friend struct mojo::StructTraits<mojom::SurfaceIdDataView, SurfaceId>;
+
   // See SurfaceIdAllocator::GenerateId.
   FrameSinkId frame_sink_id_;
   LocalFrameId local_frame_id_;

cc/surfaces/surface_reference.cc

@@ -0,0 +1,27 @@
+// 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/surface_reference.h"
+
+#include "base/strings/stringprintf.h"
+
+namespace cc {
+
+SurfaceReference::SurfaceReference() = default;
+
+SurfaceReference::SurfaceReference(const SurfaceId& parent_id,
+                                   const SurfaceId& child_id)
+    : parent_id_(parent_id), child_id_(child_id) {}
+
+SurfaceReference::SurfaceReference(const SurfaceReference& other) = default;
+
+SurfaceReference::~SurfaceReference() = default;
+
+std::string SurfaceReference::ToString() const {
+  return base::StringPrintf("parent=%s, child=%s",
+                            parent_id_.ToString().c_str(),
+                            child_id_.ToString().c_str());
+}
+
+}  // namespace cc

cc/surfaces/surface_reference.h

@@ -0,0 +1,65 @@
+// 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 CC_SURFACES_SURFACE_REFERENCE_H_
+#define CC_SURFACES_SURFACE_REFERENCE_H_
+
+#include <string>
+
+#include "base/hash.h"
+#include "cc/surfaces/surface_id.h"
+#include "mojo/public/cpp/bindings/struct_traits.h"
+
+namespace cc {
+namespace mojom {
+class SurfaceReferenceDataView;
+}
+
+// Hold a reference from an embedding (parent) to embedded (child) surface.
+class SurfaceReference {
+ public:
+  SurfaceReference();
+  SurfaceReference(const SurfaceId& parent_id, const SurfaceId& child_id);
+  SurfaceReference(const SurfaceReference& other);
+
+  ~SurfaceReference();
+
+  const SurfaceId& parent_id() const { return parent_id_; }
+  const SurfaceId& child_id() const { return child_id_; }
+
+  size_t hash() const {
+    return base::HashInts(static_cast<uint64_t>(parent_id_.hash()),
+                          static_cast<uint64_t>(child_id_.hash()));
+  }
+
+  bool operator==(const SurfaceReference& other) const {
+    return parent_id_ == other.parent_id_ && child_id_ == other.child_id_;
+  }
+
+  bool operator!=(const SurfaceReference& other) const {
+    return !(*this == other);
+  }
+
+  bool operator<(const SurfaceReference& other) const {
+    return std::tie(parent_id_, child_id_) <
+           std::tie(other.parent_id_, other.child_id_);
+  }
+
+  std::string ToString() const;
+
+ private:
+  friend struct mojo::StructTraits<mojom::SurfaceReferenceDataView,
+                                   SurfaceReference>;
+
+  SurfaceId parent_id_;
+  SurfaceId child_id_;
+};
+
+struct SurfaceReferenceHash {
+  size_t operator()(const SurfaceReference& ref) const { return ref.hash(); }
+};
+
+}  // namespace cc
+
+#endif  // CC_SURFACES_SURFACE_REFERENCE_H_