Write mojom and EnumTraits for display::HDCPState.

ui/display/mojo/display_struct_traits_unittest.cc

Index: ui/display/mojo/display_struct_traits_unittest.cc
diff --git a/ui/display/mojo/display_struct_traits_unittest.cc b/ui/display/mojo/display_struct_traits_unittest.cc
index bc3060868b8ca1f727c1060d8e79fe3b9df02051..119f7685dd1d9c4691d67755c5f6d425cd3d1287 100644
--- a/ui/display/mojo/display_struct_traits_unittest.cc
+++ b/ui/display/mojo/display_struct_traits_unittest.cc
@@ -64,6 +64,11 @@ class DisplayStructTraitsTest : public testing::Test,
     callback.Run(std::move(in));
   }
 
+  void EchoHDCPState(display::HDCPState in,
+                     const EchoHDCPStateCallback& callback) override {
+    callback.Run(in);
+  }
+
   void EchoGammaRampRGBEntry(
       const GammaRampRGBEntry& in,
       const EchoGammaRampRGBEntryCallback& callback) override {
@@ -443,4 +448,11 @@ TEST_F(DisplayStructTraitsTest, DisplaySnapshotInternal) {
   CheckDisplaySnapShotMojoEqual(*input, *output);
 }
 
+TEST_F(DisplayStructTraitsTest, HDCPStateBasic) {
+  const display::HDCPState input(HDCP_STATE_ENABLED);
+  display::HDCPState output;
+  GetTraitsTestProxy()->EchoHDCPState(input, &output);
+  EXPECT_EQ(input, output);
+}
+
 }  // namespace display