ozone: xkb: Load keymaps on worker thread & cache them

ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h

Index: ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h
diff --git a/ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h b/ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h
index d7a98545d3a435c884854f069798f9b72bcc1b4d..eba1d3518d5d47fb5ba8b8818226e12779a79c85 100644
--- a/ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h
+++ b/ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h
@@ -5,11 +5,16 @@
 #ifndef UI_EVENTS_OZONE_LAYOUT_XKB_XKB_KEYBOARD_LAYOUT_ENGINE_H_
 #define UI_EVENTS_OZONE_LAYOUT_XKB_XKB_KEYBOARD_LAYOUT_ENGINE_H_
 
+#include <map>
 #include <xkbcommon/xkbcommon.h>
 
 #include "base/containers/hash_tables.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
 #include "base/strings/string16.h"
+#include "base/task_runner.h"
 #include "ui/events/ozone/layout/events_ozone_layout_export.h"
 #include "ui/events/ozone/layout/keyboard_layout_engine.h"
 #include "ui/events/ozone/layout/xkb/scoped_xkb.h"
@@ -37,6 +42,10 @@ class EVENTS_OZONE_LAYOUT_EXPORT XkbKeyboardLayoutEngine
                       KeyboardCode* key_code,
                       uint32* platform_keycode) const override;
 
+  // Gets the names of the RMLO rule for libxkbcommon.
+  // Makes it protected for testing.
+  scoped_ptr<xkb_rule_names> GetXkbRuleNames(const std::string& layout_name);
+
  protected:
   // Table for EventFlagsToXkbFlags().
   struct XkbFlagMapEntry {
@@ -60,6 +69,7 @@ class EVENTS_OZONE_LAYOUT_EXPORT XkbKeyboardLayoutEngine
   const XkbKeyCodeConverter& key_code_converter_;
 
  private:
+
   // Sets a new XKB keymap. This updates xkb_state_ (which takes ownership
   // of the keymap), and updates xkb_flag_map_ for the new keymap.
   void SetKeymap(xkb_keymap* keymap);
@@ -82,10 +92,22 @@ class EVENTS_OZONE_LAYOUT_EXPORT XkbKeyboardLayoutEngine
                                base::char16 base_character,
                                int ui_flags) const;
 
+  // Callback when keymap file is loaded complete.
+  void OnKeymapLoaded(const std::string& layout_name, xkb_keymap* keymap);
+
   // libxkbcommon uses explicit reference counting for its structures,
   // so we need to trigger its cleanup.
   scoped_ptr<xkb_context, XkbContextDeleter> xkb_context_;
   scoped_ptr<xkb_state, XkbStateDeleter> xkb_state_;
+  std::map<std::string, xkb_keymap*> xkb_keymaps_;
+
+  std::string current_layout_name_;
+
+  // Task runner for event dispatch.
+  scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
+
+  // Support weak pointers for attach & detach callbacks.
+  base::WeakPtrFactory<XkbKeyboardLayoutEngine> weak_ptr_factory_;
 };
 
 }  // namespace ui