Make backspace not go back while IME is active.

chrome/common/native_web_keyboard_event.h

Index: chrome/common/native_web_keyboard_event.h
diff --git a/chrome/common/native_web_keyboard_event.h b/chrome/common/native_web_keyboard_event.h
index 87f5a90507c13c52d9ee78ced662cf325434adc5..654c38bf6c16f06219c4277afb863bc0a6be1e35 100644
--- a/chrome/common/native_web_keyboard_event.h
+++ b/chrome/common/native_web_keyboard_event.h
@@ -48,6 +48,12 @@ struct NativeWebKeyboardEvent : public WebKit::WebKeyboardEvent {
   MSG os_event;
 #elif defined(OS_MACOSX)
   NSEvent* os_event;
+
+  // True if the browser should ignore this event if it's not handled by the
+  // renderer. This happens for RawKeyDown events that are created while IME is
+  // active and is necessary to prevent backspace from doing "history back" if
+  // it is hit in ime mode.
+  bool skip_in_browser;
 #elif defined(OS_LINUX)
   GdkEventKey* os_event;
 #endif