[DomKey] Support Japanese (JIS) layout special keys

ui/events/keycodes/platform_key_map_win.cc

Index: ui/events/keycodes/platform_key_map_win.cc
diff --git a/ui/events/keycodes/platform_key_map_win.cc b/ui/events/keycodes/platform_key_map_win.cc
index 593e386936dd4167f21ca08105d0024186715185..00b24f49e77cfe138a41b99dcc773d52fcabd666 100644
--- a/ui/events/keycodes/platform_key_map_win.cc
+++ b/ui/events/keycodes/platform_key_map_win.cc
@@ -209,15 +209,40 @@ DomKey LanguageSpecificOemKeyboardCodeToDomKey(KeyboardCode key_code,
       default:
         return DomKey::NONE;
     }
+  } else if (primary_language == LANG_JAPANESE) {
+    switch (key_code) {
+      case VKEY_KANA:
+        return DomKey::KANA_MODE;

[chongz, 2016/07/06 22:50:34]

|VKEY_KANA| is not used with modern Japanese keyboard (they use |VKEY_ATTN|
instead), but we want to match FF and IE to support it.

https://hg.mozilla.org/integration/mozilla-inbound/rev/b5fddca814e0#l1.146

[Wez, 2016/07/07 18:25:51]

When you say "modern keyboard" do you mean modern Japanese layouts have switched
to VKEY_ATTN?

Suggest merging this with the VKEY_ATTN switch case, so it's more obvious that
the two values generate the same output.

You might add a comment saying that some Japanese layouts used VKEY_KANA for
KANA_MODE, while others use VKEY_ATTN, so we map them both for compatibility.

[chongz, 2016/07/07 22:18:09]

Actually FireFox says so but I cannot find more info about VK_KANA. However at
least my keyboard is producing VK_ATTN on Win 10, and I cannot figure out how to
produce VK_KANA using it.
Done.

[Wez, 2016/07/08 23:34:06]

That's really unfortunate. It sounds like the Firefox rationale was that it
exists and when they injected it into IE it had generated KanaMode, so we should
make sure our comment reflects that, e.g:

"VKEY_KANA isn't generated by any modern layouts but is a listed value that
third-party apps might synthesize, so we handle it anyway."

+      case VKEY_KANJI:
+        return DomKey::KANJI_MODE;
+      case VKEY_OEM_ATTN:
+        return DomKey::ALPHANUMERIC;
+      case VKEY_OEM_FINISH:
+        return DomKey::KATAKANA;
+      case VKEY_OEM_COPY:
+        return DomKey::HIRAGANA;
+      case VKEY_DBE_SBCSCHAR:
+        return DomKey::HANKAKU;
+      case VKEY_DBE_DBCSCHAR:
+        return DomKey::ZENKAKU;
+      case VKEY_OEM_BACKTAB:
+        return DomKey::ROMAJI;
+      case VKEY_ATTN:
+        return DomKey::KANA_MODE;

[chongz, 2016/07/06 22:50:34]

On other layouts |VKEY_ATTN| will be mapped to |DomKey::ATTN|.

+      default:
+        return DomKey::NONE;
+    }
   }
-  // TODO(chongz): Handle Japanese keyboard layout keys 0xF0..0xF5, VKEY_KANA,
-  // VKEY_KANJI.
-  // https://crbug.com/612694
   return DomKey::NONE;
 }
 
 DomKey NonPrintableKeyboardCodeToDomKey(KeyboardCode key_code, HKL layout) {
-  // 1. Most |key_codes| have the same meaning regardless of |layout|.
+  // 1. Check if |key_code| has a |layout|-specific meaning.
+  const DomKey key = LanguageSpecificOemKeyboardCodeToDomKey(key_code, layout);
+  if (key != DomKey::NONE)
+    return key;

[chongz, 2016/07/06 22:50:34]

Do language mapping first so JIS could map |VKEY_ATTN| to |DomKey::KANA_MODE|.

[Wez, 2016/07/07 18:25:51]

Acknowledged.

+
+  // 2. Most |key_codes| have the same meaning regardless of |layout|.
   const NonPrintableKeyEntry* result = std::lower_bound(
       std::begin(kNonPrintableKeyMap), std::end(kNonPrintableKeyMap), key_code,
       [](const NonPrintableKeyEntry& entry, KeyboardCode needle) {
@@ -225,8 +250,8 @@ DomKey NonPrintableKeyboardCodeToDomKey(KeyboardCode key_code, HKL layout) {
       });
   if (result != std::end(kNonPrintableKeyMap) && result->key_code == key_code)
     return result->dom_key;
-  // 2. Look up a |layout|-specific meaning for |key_code|.
-  return LanguageSpecificOemKeyboardCodeToDomKey(key_code, layout);
+
+  return DomKey::NONE;
 }
 
 void CleanupKeyMapTls(void* data) {
@@ -280,11 +305,12 @@ DomKey PlatformKeyMap::DomKeyFromKeyboardCodeImpl(KeyboardCode key_code,
     if (it != printable_keycode_to_key_.end()) {
       key = it->second;
       if (key != DomKey::NONE)
-        break;
+        return key;
     }
   }
 
-  return key;
+  // Return DomKey::UNIDENTIFIED to prevent US layout fall-back.
+  return DomKey::UNIDENTIFIED;

[chongz, 2016/07/06 22:50:34]

|KeyEvent::ApplyLayout()| will do the fall-back mapping |DomCode->DomKey| if the
key is |DomKey::NONE|.

We want to avoid that so |KanaMode| key could produce "Unidentified" on
non-Japanese layout. (DomCode is still "KanaMode")

[Wez, 2016/07/07 18:25:51]

Acknowledged.

 }
 
 // static