Introduce cc StructTraits unit tests

cc/ipc/struct_traits_unittest.cc

+// 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 "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "cc/ipc/traits_test_service.mojom.h"
+#include "cc/quads/render_pass_id.h"
+#include "mojo/public/cpp/bindings/binding_set.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+
+namespace {
+
+class StructTraitsTest : public testing::Test, public mojom::TraitsTestService {
+ public:
+  StructTraitsTest() {}
+
+ protected:
+  mojom::TraitsTestServicePtr GetTraitsTestProxy() {
+    return traits_test_bindings_.CreateInterfacePtrAndBind(this);
+  }
+
+ private:
+  // TraitsTestService:
+  void EchoRenderPassId(const RenderPassId& r,
+                        const EchoRenderPassIdCallback& callback) override {
+    callback.Run(r);
+  }
+
+  void EchoSurfaceId(const SurfaceId& s,
+                     const EchoSurfaceIdCallback& callback) override {
+    callback.Run(s);
+  }
+
+  mojo::BindingSet<TraitsTestService> traits_test_bindings_;
+};
+
+}  // namespace
+
+TEST_F(StructTraitsTest, RenderPassId) {
+  const int layer_id = 1337;
+  const uint32_t index = 0xdeadbeef;
+  RenderPassId input(layer_id, index);
+  base::RunLoop loop;
+  mojom::TraitsTestServicePtr proxy = GetTraitsTestProxy();
+  proxy->EchoRenderPassId(input, [&](const RenderPassId& pass) {

[Tom Sepez, 2016/05/31 16:07:43]

I'd expect we'd capture layer_id and index by value, and test against them, so
as to be immune to any unexpected transformation of |input|.

[Fady Samuel, 2016/05/31 16:37:09]

I'm passing all of input by value now. WDYT? 

+    EXPECT_EQ(input.layer_id, pass.layer_id);
+    EXPECT_EQ(input.index, pass.index);
+    loop.Quit();
+  });
+  loop.Run();
+}
+
+TEST_F(StructTraitsTest, SurfaceId) {
+  const uint32_t id_namespace = 1337;
+  const uint32_t local_id = 0xfbadbeef;
+  const uint64_t nonce = 0xdeadbeef;
+  SurfaceId input(id_namespace, local_id, nonce);
+  base::RunLoop loop;
+  mojom::TraitsTestServicePtr proxy = GetTraitsTestProxy();
+  proxy->EchoSurfaceId(input, [&](const SurfaceId& pass) {
+    EXPECT_EQ(input.id_namespace(), pass.id_namespace());

[Tom Sepez, 2016/05/31 16:07:42]

same here.

[Fady Samuel, 2016/05/31 16:37:09]

Passing input by value.

+    EXPECT_EQ(input.local_id(), pass.local_id());
+    EXPECT_EQ(input.nonce(), pass.nonce());
+    loop.Quit();
+  });
+  loop.Run();
+}
+
+}  // namespace cc