Add more out of line copy ctors for complex classes.

chrome/browser/ui/input_method/input_method_engine_base.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_INPUT_METHOD_INPUT_METHOD_ENGINE_BASE_H_
 #define CHROME_BROWSER_UI_INPUT_METHOD_INPUT_METHOD_ENGINE_BASE_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 10 matching lines @@
 class IMEEngineHandlerInterface;
 class KeyEvent;
 }  // namespace ui
 
 namespace input_method {
 
 class InputMethodEngineBase : virtual public ui::IMEEngineHandlerInterface {
  public:
   struct KeyboardEvent {
     KeyboardEvent();
+    KeyboardEvent(const KeyboardEvent& other);
     virtual ~KeyboardEvent();
 
     std::string type;
     std::string key;
     std::string code;
     int key_code;  // only used by on-screen keyboards.
     std::string extension_id;
     bool alt_key;
     bool ctrl_key;
     bool shift_key;
@@ skipping 190 matching lines @@
   std::string text_;
 
   // Indicates whether the IME extension is currently handling a physical key
   // event. This is used in CommitText/UpdateCompositionText/etc.
   bool handling_key_event_;
 };
 
 }  // namespace input_method
 
 #endif  // CHROME_BROWSER_UI_INPUT_METHOD_INPUT_METHOD_ENGINE_BASE_H_