ozone: Do not let LinuxUi set self as input method context factory.

Instead, we delegate creating the input method to OzonePlatforms.
And if the linux ui set self as the factory, the ozone never
creates a context factory and uses GtkUi impl, which is no-op
for ozone.

Bug: 1000127
Change-Id: Ie9c3723454aeed586c2e1d4df66ef26e8fdb9b44
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1781459Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Cr-Commit-Position: refs/heads/master@{#693019}

ui/views/linux_ui/linux_ui.cc

@@ -19,7 +19,12 @@ namespace views {
 void LinuxUI::SetInstance(LinuxUI* instance) {
   delete g_linux_ui;
   g_linux_ui = instance;
+// Do not set IME instance for ozone as we delegate creating the input method to
+// OzonePlatforms instead. If this is set, OzonePlatform never sets a context
+// factory.
+#if !defined(USE_OZONE)
   LinuxInputMethodContextFactory::SetInstance(instance);
+#endif
   SkiaFontDelegate::SetInstance(instance);
   ShellDialogLinux::SetInstance(instance);
   ui::SetTextEditKeyBindingsDelegate(instance);