Write mojom and StructTraits for DisplaySnapshot.

ui/display/types/display_mode.cc

Index: ui/display/types/display_mode.cc
diff --git a/ui/display/types/display_mode.cc b/ui/display/types/display_mode.cc
index 6d43caa5638406c5e43a4b7003d0e491db066715..b44970ac3e9b05634d4fd9c05b5eae719073a4d3 100644
--- a/ui/display/types/display_mode.cc
+++ b/ui/display/types/display_mode.cc
@@ -18,10 +18,18 @@ DisplayMode::DisplayMode(const gfx::Size& size,
 
 DisplayMode::~DisplayMode() {}
 
+bool DisplayMode::operator==(const DisplayMode& other) const {
+  return this->size() == other.size() &&
+         this->is_interlaced() == other.is_interlaced() &&
+         this->refresh_rate() == other.refresh_rate();
+}
+
+bool DisplayMode::operator!=(const DisplayMode& other) const {
+  return !operator==(other);
+}
+
 std::unique_ptr<DisplayMode> DisplayMode::Clone() const {
-  return base::WrapUnique(new DisplayMode(size_,
-                                          is_interlaced_,
-                                          refresh_rate_));
+  return base::MakeUnique<DisplayMode>(size_, is_interlaced_, refresh_rate_);
 }
 
 std::string DisplayMode::ToString() const {