[InputEvent] Add 'beforeinput' logic in |will*()| and guarded by a flag (3/11)

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

 /*
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 2141 matching lines @@
 
 InputEvent::EventIsComposing isComposingFromCommand(
     const CompositeEditCommand* command) {
   if (command->isTypingCommand() &&
       toTypingCommand(command)->compositionType() !=
           TypingCommand::TextCompositionNone)
     return InputEvent::IsComposing;
   return InputEvent::NotComposing;
 }
 
+bool dispatchBeforeInputEvent(EditCommandSource source,
+                              LocalFrame* frame,
+                              Node* target,
+                              InputEvent::InputType inputType,
+                              const String& data,
+                              DataTransfer* dataTransfer,
+                              InputEvent::EventCancelable isCancelable,
+                              InputEvent::EventIsComposing isComposing,
+                              const RangeVector* ranges) {
+  // Don't fire 'beforeinput', return true to continue.
+  if (source != EditCommandSource::kMenuOrKeyBinding ||
+      inputType == InputEvent::InputType::None)
+    return true;
+  if (!RuntimeEnabledFeatures::inputEventEnabled())
+    return true;
+  if (!frame || !target || !target->isConnected())
+    return true;
+
+  if (!hasRichlyEditableStyle(*target)) {
+    // Plain-text only elements (<input>, <textarea>, etc.) don't support
+    // DataTransfer or Range.
+    dataTransfer = nullptr;
+    ranges = nullptr;
+  }
+
+  InputEvent* beforeInputEvent;
+
+  if (dataTransfer) {
+    beforeInputEvent = InputEvent::createBeforeInput(
+        inputType, dataTransfer, isCancelable, isComposing, ranges);
+  } else {
+    beforeInputEvent = InputEvent::createBeforeInput(
+        inputType, data, isCancelable, isComposing, ranges);
+  }
+
+  DispatchEventResult result = target->dispatchEvent(beforeInputEvent);
+  // 'beforeinput' event handler may destroy target frame.
+  if (!frame->document() || frame->document()->frame() != frame ||
+      !target->isConnected())
+    return false;
+  return result == DispatchEventResult::NotCanceled;
+}
+
 }  // namespace blink