CopyOutputResult must have a working release callback when received over mojo

cc/ipc/copy_output_result_struct_traits.h

 // Copyright 2017 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_COPY_OUTPUT_RESULT_STRUCT_TRAITS_H_
 #define CC_IPC_COPY_OUTPUT_RESULT_STRUCT_TRAITS_H_
 
 #include "cc/ipc/copy_output_result.mojom-shared.h"
+#include "cc/ipc/texture_mailbox_releaser.mojom.h"
 #include "cc/ipc/texture_mailbox_struct_traits.h"
 #include "cc/output/copy_output_result.h"
 #include "skia/public/interfaces/bitmap_skbitmap_struct_traits.h"
 #include "ui/gfx/geometry/mojo/geometry_struct_traits.h"
 
+namespace cc {
+
+struct TextureMailboxWithRelease {
+  TextureMailbox texture_mailbox;
+  mojom::TextureMailboxReleaserPtr releaser;
+
+  DISALLOW_COPY_AND_ASSIGN(TextureMailboxWithRelease);
+};
+
+}  // namespace cc
+
 namespace mojo {
 
 template <>
 struct StructTraits<cc::mojom::CopyOutputResultDataView,
                     std::unique_ptr<cc::CopyOutputResult>> {
+  static bool IsNull(const std::unique_ptr<cc::CopyOutputResult>& result) {

[danakj, 2017/02/13 18:41:05]

What do these have to do with having the sub type?

+    return result->IsEmpty();
+  }
+
+  static void SetToNull(std::unique_ptr<cc::CopyOutputResult>* out) {
+    *out = cc::CopyOutputResult::CreateEmptyResult();
+  }
+
   static const gfx::Size& size(
       const std::unique_ptr<cc::CopyOutputResult>& result) {
     return result->size_;
   }
 
   static const SkBitmap& bitmap(
       const std::unique_ptr<cc::CopyOutputResult>& result);
 
-  static const cc::TextureMailbox& texture_mailbox(
-      const std::unique_ptr<cc::CopyOutputResult>& result) {
-    return result->texture_mailbox_;
-  }
+  static const cc::TextureMailboxWithRelease& texture_mailbox(
+      const std::unique_ptr<cc::CopyOutputResult>& result);
 
   static bool Read(cc::mojom::CopyOutputResultDataView data,
                    std::unique_ptr<cc::CopyOutputResult>* out_p);
 };
 
+template <>
+struct StructTraits<cc::mojom::TextureMailboxWithReleaseDataView,
+                    cc::TextureMailboxWithRelease> {
+  static const cc::TextureMailbox& texture_mailbox(
+      const cc::TextureMailboxWithRelease& input) {
+    return input.texture_mailbox;
+  }
+
+  static cc::mojom::TextureMailboxReleaserPtr releaser(
+      const cc::TextureMailboxWithRelease& input) {
+    return std::move(input.releaser);
+  }
+
+  static bool Read(cc::mojom::TextureMailboxWithReleaseDataView data,
+                   cc::TextureMailboxWithRelease* out_p);
+};
+
 }  // namespace mojo
 
 #endif  // CC_IPC_COPY_OUTPUT_RESULT_STRUCT_TRAITS_H_