Add a CodeToNativeKeycode helper that converts UIEvent code to native code.

ui/base/keycodes/usb_keycode_map_unittest.cc

Index: ui/base/keycodes/usb_keycode_map_unittest.cc
diff --git a/ui/base/keycodes/usb_keycode_map_unittest.cc b/ui/base/keycodes/usb_keycode_map_unittest.cc
index 5b09715ae98ebecffa5706012789f022386bc59d..14b41786049e6263513931c61b2b1f754a81f165 100644
--- a/ui/base/keycodes/usb_keycode_map_unittest.cc
+++ b/ui/base/keycodes/usb_keycode_map_unittest.cc
@@ -33,6 +33,8 @@ TEST(UsbKeycodeMap, Basic) {
   // Verify that the first element in the table is the "invalid" code.
   EXPECT_EQ(InvalidUsbKeycode(), usb_keycode_map[0].usb_keycode);
   EXPECT_EQ(InvalidNativeKeycode(), usb_keycode_map[0].native_keycode);
+  EXPECT_EQ(InvalidKeyboardEventCode(), "Unidentified");
+  EXPECT_EQ(InvalidNativeKeycode(), CodeToNativeKeycode("Unidentified"));
 
   // Verify that there are no duplicate entries in the mapping.
   std::map<uint32_t, uint16_t> usb_to_native;
@@ -46,6 +48,18 @@ TEST(UsbKeycodeMap, Basic) {
     EXPECT_EQ(usb_keycode_map[i].native_keycode,
               UsbKeycodeToNativeKeycode(usb_keycode_map[i].usb_keycode));
 
+    // Verify CodeToNativeKeycode and NativeKeycodeToCode work correctly.
+    if (usb_keycode_map[i].code) {
+      EXPECT_EQ(usb_keycode_map[i].native_keycode,
+                CodeToNativeKeycode(usb_keycode_map[i].code));
+      EXPECT_EQ(usb_keycode_map[i].code,
+                NativeKeycodeToCode(usb_keycode_map[i].native_keycode));
+    }
+    else {
+      EXPECT_EQ(InvalidNativeKeycode(),
+                CodeToNativeKeycode(usb_keycode_map[i].code));
+    }
+
     // Verify that the USB or native codes aren't duplicated.
     EXPECT_EQ(0U, usb_to_native.count(usb_keycode_map[i].usb_keycode))
         << " duplicate of USB code 0x" << std::hex << std::setfill('0')