Fix clang build break

chrome/browser/chromeos/input_method/input_method_engine.h

Index: chrome/browser/chromeos/input_method/input_method_engine.h
diff --git a/chrome/browser/chromeos/input_method/input_method_engine.h b/chrome/browser/chromeos/input_method/input_method_engine.h
index e63ac20f2b48deb9028233ec696281845ada60de..0a0e7a19ddfe09a858fd145a2cbdd93fab4791cb 100644
--- a/chrome/browser/chromeos/input_method/input_method_engine.h
+++ b/chrome/browser/chromeos/input_method/input_method_engine.h
@@ -18,6 +18,9 @@ extern const char* kExtensionImePrefix;
 class InputMethodEngine {
  public:
   struct KeyboardEvent {
+    KeyboardEvent();
+    virtual ~KeyboardEvent();
+
     std::string type;
     std::string key;
     std::string key_code;
@@ -27,6 +30,9 @@ class InputMethodEngine {
   };
 
   struct MenuItem {
+    MenuItem();
+    virtual ~MenuItem();
+
     std::string id;
     std::string label;
     int style;
@@ -44,6 +50,9 @@ class InputMethodEngine {
   };
 
   struct Candidate {
+    Candidate();
+    virtual ~Candidate();
+
     std::string value;
     int id;
     std::string label;