Add a crosapi flag for exo to support ime without workaround.

Adding a flag for the IME support which doesn't need the
ConsumedByIme() workaround.
When the flag kSupported is specified as a Lacros's init param,
Lacros expects that the key events and keysym events are sent
in separated APIs without filtered by ConsumedByIme().
exo's new behavior for this new flag is implemented in a follow-up CL.

Bug: 1093194
Test: None
Change-Id: Id01aa2b064fff6db6fe7420c42e39a99b9c87866
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2631545
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844466}

chromeos/crosapi/mojom/crosapi.mojom

@@ -200,9 +200,12 @@ enum ExoImeSupport {
   // Note that this is an approach consistent with ARC's behavior.
   kConsumedByImeWorkaround = 1,
 
-  // TODO(crbug.com/1093194): For long term, we're looking at a way to remove
-  // the above workaround. It will be exclusive state, so on implementing
-  // ash-chrome's fix, it is necessary to add a new value here, too, atomically.
+  // Exo sends keysym events to a client using a separate API.
+  // Once the client (lacros-chrome) gets ready to handle wl_keyboard::key and
+  // zwp_text_input_v1::keysym properly in separate paths, exo can send each
+  // each event without the ConsumedByIme() workaround above and tell the client
+  // that it dropped the workaround using kSupported flag.
+  [MinVersion=1] kSupported = 2,
 };
 
 // LacrosInitParams is a set of parameters for initialization of lacros-chrome,

ui/ozone/platform/wayland/host/wayland_input_method_context.cc

@@ -74,9 +74,8 @@ bool IsImeEnabled() {
   // world becomes new enough.
   const crosapi::mojom::LacrosInitParams* init_params =
       lacros_chrome_service->init_params();
-  if (init_params &&
-      init_params->exo_ime_support ==
-          crosapi::mojom::ExoImeSupport::kConsumedByImeWorkaround) {
+  if (init_params && init_params->exo_ime_support !=
+                         crosapi::mojom::ExoImeSupport::kUnsupported) {
     return true;
   }
 #endif