Write mojom and StructTraits for DisplaySnapshot.

ui/display/display_snapshot_mojo.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 UI_DISPLAY_DISPLAY_SNAPSHOT_MOJO_H_
+#define UI_DISPLAY_DISPLAY_SNAPSHOT_MOJO_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "ui/display/display_export.h"
+#include "ui/display/types/display_snapshot.h"
+
+namespace display {
+
+// DisplaySnapshot implementation that can be used with Mojo IPC.

[rjkroege, 2017/03/01 15:46:27]

This exists because we have a refactoring that's not done right? Because really
we could use the mojo struct everywhere in the future? In which case, could you
note/record this in a TODO and/or a bug before landing so that this code cleanup
actually happens.

[thanhph1, 2017/03/01 16:29:07]

Sounds good! We have this class because we can't instantiate DisplaySnapShot due
to ToString() method. I added
https://bugs.chromium.org/p/chromium/issues/detail?id=697475 to easily track our
cleanup efforts in the future.

+class DISPLAY_EXPORT DisplaySnapshotMojo : public DisplaySnapshot {
+ public:
+  DisplaySnapshotMojo(int64_t display_id,
+                      const gfx::Point& origin,
+                      const gfx::Size& physical_size,
+                      DisplayConnectionType type,
+                      bool is_aspect_preserving_scaling,
+                      bool has_overscan,
+                      bool has_color_correction_matrix,
+                      std::string display_name,
+                      const base::FilePath& sys_path,
+                      int64_t product_id,
+                      DisplayModeList modes,
+                      const std::vector<uint8_t>& edid,
+                      const DisplayMode* current_mode,
+                      const DisplayMode* native_mode,
+                      const gfx::Size& maximum_cursor_size);
+  ~DisplaySnapshotMojo() override;
+  std::unique_ptr<DisplaySnapshotMojo> Clone() const;
+
+  // DisplaySnapshot:
+  std::string ToString() const override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DisplaySnapshotMojo);
+};
+
+}  // namespace display
+
+#endif  // UI_DISPLAY_DISPLAY_SNAPSHOT_MOJO_H_