CopyOutputResult must have a working release callback when received over mojo

cc/ipc/struct_traits_unittest.cc

Index: cc/ipc/struct_traits_unittest.cc
diff --git a/cc/ipc/struct_traits_unittest.cc b/cc/ipc/struct_traits_unittest.cc
index 5d22e492c579dd577f6d3141de592f2a9663a9d4..6f4e318c9e03537fee860008652564521ab8c1ec 100644
--- a/cc/ipc/struct_traits_unittest.cc
+++ b/cc/ipc/struct_traits_unittest.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "cc/input/selection.h"
 #include "cc/ipc/traits_test_service.mojom.h"
 #include "cc/output/copy_output_result.h"
@@ -91,6 +92,12 @@ class StructTraitsTest : public testing::Test, public mojom::TraitsTestService {
     callback.Run(s);
   }
 
+  void EchoSingleReleaseCallback(
+      std::unique_ptr<SingleReleaseCallback> s,
+      const EchoSingleReleaseCallbackCallback& callback) override {
+    callback.Run(std::move(s));
+  }
+
   void EchoSharedQuadState(
       const SharedQuadState& s,
       const EchoSharedQuadStateCallback& callback) override {
@@ -129,6 +136,26 @@ class StructTraitsTest : public testing::Test, public mojom::TraitsTestService {
   DISALLOW_COPY_AND_ASSIGN(StructTraitsTest);
 };
 
+class TextureMailboxReleaserImpl : public mojom::TextureMailboxReleaser {
+ public:
+  TextureMailboxReleaserImpl(mojom::TextureMailboxReleaserRequest request,
+                             base::Closure quit_closure)
+      : quit_closure_(quit_closure), binding_(this, std::move(request)) {}
+
+  bool is_called() { return is_called_; }
+
+  // mojom::TextureMailboxReleaser implementation:
+  void Release(const gpu::SyncToken& sync_token, bool is_lost) override {
+    is_called_ = true;
+    quit_closure_.Run();
+  }
+
+ private:
+  bool is_called_ = false;
+  base::Closure quit_closure_;
+  mojo::Binding<mojom::TextureMailboxReleaser> binding_;
+};
+
 void StubCopyOutputRequestCallback(std::unique_ptr<CopyOutputResult> result) {}
 
 void StubCopyOutputResultCallback(const gpu::SyncToken& sync_token,
@@ -861,6 +888,23 @@ TEST_F(StructTraitsTest, Selection) {
   EXPECT_EQ(is_empty_text_form_control, output.is_empty_text_form_control);
 }
 
+TEST_F(StructTraitsTest, SingleReleaseCallback) {
+  base::RunLoop run_loop;
+  mojom::TextureMailboxReleaserPtr releaser;
+  TextureMailboxReleaserImpl impl(MakeRequest(&releaser),
+                                  run_loop.QuitClosure());
+  auto input = SingleReleaseCallback::Create(std::move(releaser));
+
+  mojom::TraitsTestServicePtr proxy = GetTraitsTestProxy();
+  std::unique_ptr<SingleReleaseCallback> output;
+  proxy->EchoSingleReleaseCallback(std::move(input), &output);
+
+  EXPECT_FALSE(impl.is_called());
+  output->Run(gpu::SyncToken(), true);
+  run_loop.Run();
+  EXPECT_TRUE(impl.is_called());
+}
+
 TEST_F(StructTraitsTest, SurfaceId) {
   static constexpr FrameSinkId frame_sink_id(1337, 1234);
   static LocalSurfaceId local_surface_id(0xfbadbeef,