Implemented StructTraits for cc::CopyOutputResult

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/output/copy_output_result.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<cc::mojom::CopyOutputResultDataView, cc::CopyOutputResult> {
+  static const gfx::Size& size(const cc::CopyOutputResult& result) {
+    return result.size_;
+  }
+
+  static const SkBitmap& bitmap(const cc::CopyOutputResult& result) {
+    static SkBitmap null_bitmap;

[vmpstr, 2017/01/31 21:32:19]

nit: empty_bitmap

[Ken Rockot(use gerrit already), 2017/01/31 21:46:20]

Per the ongoing discussion linked earlier, please also make this a SkBitmap* and
allocate it on the heap so it just leaks on shutdown. We don't want local
statics running destructors on shutdown.

[Saman Sami, 2017/02/01 15:51:57]

Done.

[Saman Sami, 2017/02/01 15:51:57]

This is a null bitmap though. IsNull() returns true. Mojo also uses the term
"null".

[Ken Rockot(use gerrit already), 2017/02/01 16:04:55]

And perhaps more importantly, IsNull() returns true iff SkBitmap::is_null
returns true. So the meaning of "null" is consistent here. Furthermore, SkBitmap
also defines empty() which does not mean the same thing.

+    if (!result.bitmap_)
+      return null_bitmap;
+    return *result.bitmap_;
+  }
+
+  static const cc::TextureMailbox& texture_mailbox(
+      const cc::CopyOutputResult& result) {
+    return result.texture_mailbox_;
+  }
+
+  static bool Read(cc::mojom::CopyOutputResultDataView data,

[Ken Rockot(use gerrit already), 2017/01/31 21:46:20]

nit: (sorry, overlooked this earlier) Please define this out-of-line by moving
it to a cc file. Same for bitmap() since it's non-trivial.

[Saman Sami, 2017/02/01 15:51:57]

Done.

+                   cc::CopyOutputResult* out) {
+    out->bitmap_ = base::MakeUnique<SkBitmap>();
+    return data.ReadSize(&out->size_) && data.ReadBitmap(out->bitmap_.get()) &&
+           data.ReadTextureMailbox(&out->texture_mailbox_);
+  }
+};
+
+}  // namespace mojo
+
+#endif  // CC_IPC_COPY_OUTPUT_RESULT_STRUCT_TRAITS_H_