Put kSkipImeProcessing property on ARC++ notification surfaces.

ARC++ notification can have an input field. ARC++ notification should
have kSkipImeProcessing property to support text input with
ArcPreImeKeyEventSupport feature.

Bug: b:148193316
Test: Can delete characters by backspace on text input on a notification.
Change-Id: I4a2644e7079be21122228aaee6ac31beb3838206
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2391421Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804641}

ash/public/cpp/external_arc/BUILD.gn

@@ -31,6 +31,7 @@ static_library("external_arc") {
   deps = [
     "//ash/public/cpp",
     "//base",
+    "//chromeos/constants",
     "//components/account_id",
     "//components/arc:arc_metrics_constants",
     "//components/arc:connection_holder",

ash/public/cpp/external_arc/message_center/arc_notification_surface_impl.cc

@@ -5,8 +5,11 @@
 #include "ash/public/cpp/external_arc/message_center/arc_notification_surface_impl.h"
 
 #include "base/check_op.h"
+#include "base/feature_list.h"
+#include "chromeos/constants/chromeos_features.h"
 #include "components/exo/notification_surface.h"
 #include "components/exo/surface.h"
+#include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_delegate.h"
 #include "ui/base/cursor/cursor.h"
@@ -88,6 +91,13 @@ ArcNotificationSurfaceImpl::ArcNotificationSurfaceImpl(
   native_view_->Init(ui::LAYER_NOT_DRAWN);
   native_view_->SetName("ArcNotificationSurface");
   native_view_->AddChild(surface_->host_window());
+
+  if (base::FeatureList::IsEnabled(
+          chromeos::features::kArcPreImeKeyEventSupport)) {
+    surface_->root_surface()->window()->SetProperty(
+        aura::client::kSkipImeProcessing, true);
+  }
+
   native_view_->Show();
 }