Write mojom and StructTraits for DisplaySnapshot.

ui/display/display_snapshot_mojo.h

Index: ui/display/display_snapshot_mojo.h
diff --git a/ui/display/display_snapshot_mojo.h b/ui/display/display_snapshot_mojo.h
new file mode 100644
index 0000000000000000000000000000000000000000..90b71291d902e96fb3954321b4b370fad271dfff
--- /dev/null
+++ b/ui/display/display_snapshot_mojo.h
@@ -0,0 +1,41 @@
+// 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 "base/macros.h"
+#include "ui/display/display_export.h"
+#include "ui/display/types/display_snapshot.h"
+
+namespace display {
+
+// This class is used to create DisplaySnapshot IPC struct traits.

[kylechar, 2017/02/14 21:35:28]

I don't know if I would say this class exists to create DisplaySnapshot
StructTraits. That is what you are doing but it's not the "why". You need to be
able to send DisplaySnapshot over Mojo IPC, hence the class.

// DisplaySnapshot implementation that can be used with Mojo IPC.

[thanhph1, 2017/02/15 15:37:55]

Done.

+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::string ToString() const override;

[kylechar, 2017/02/14 21:35:28]

You need to list what class you're overriding from before a block of methods.
This doesn't apply to the destructor.

// DisplaySnapshot:
std::string ToString() const override;

[thanhph1, 2017/02/15 15:37:55]

Done.

+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DisplaySnapshotMojo);
+};
+
+}  // namespace display
+
+#endif  // UI_DISPLAY_DISPLAY_SNAPSHOT_MOJO_H_