[InputEvent] Fire 'beforeinput' during typing, pressing hot keys and IME composition

third_party/WebKit/Source/core/editing/InputMethodController.cpp

Index: third_party/WebKit/Source/core/editing/InputMethodController.cpp
diff --git a/third_party/WebKit/Source/core/editing/InputMethodController.cpp b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
index 7aeb0d1f45878ec10d499195a6e38f8e40180923..d6ace09dd986e0797011b1dc2899a3e5e01e448d 100644
--- a/third_party/WebKit/Source/core/editing/InputMethodController.cpp
+++ b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
@@ -169,6 +169,12 @@ bool InputMethodController::confirmComposition(const String& text)
 
     clear();
 
+    // According to spec 'beforeinput' should not be sent along with  CompositionEnd, so
+    // dispatch after CompositionEnd if there is any update.
+    // https://w3c.github.io/uievents/#h-events-composition-event-input-events
+    if (dispatchBeforeInputInsertText(frame().document()->focusedElement(), text) != DispatchEventResult::NotCanceled)
+        return false;
+
     insertTextForConfirmedComposition(text);
 
     return true;
@@ -179,6 +185,10 @@ bool InputMethodController::confirmCompositionOrInsertText(const String& text, C
     if (!hasComposition()) {
         if (!text.length())
             return false;
+
+        if (dispatchBeforeInputInsertText(frame().document()->focusedElement(), text) != DispatchEventResult::NotCanceled)
+            return false;
+
         editor().insertText(text, 0);
         return true;
     }
@@ -275,8 +285,12 @@ void InputMethodController::setComposition(const String& text, const Vector<Comp
             else
                 event = CompositionEvent::create(EventTypeNames::compositionend, frame().domWindow(), text);
         }
-        if (event.get())
+        if (event.get()) {
+            // TODO(chongz): Support canceling IME composition.
+            if (event->type() == EventTypeNames::compositionupdate)
+                dispatchBeforeInputCompositionUpdate(target, text);
             target->dispatchEvent(event);
+        }
     }
 
     // If text is empty, then delete the old composition here. If text is non-empty, InsertTextCommand::input