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

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

Index: third_party/WebKit/Source/core/editing/EditingUtilities.cpp
diff --git a/third_party/WebKit/Source/core/editing/EditingUtilities.cpp b/third_party/WebKit/Source/core/editing/EditingUtilities.cpp
index b2e9585120c4d712818d6efd21dd2340888b1568..97baca85b3bf6c1f4ad03bcc8d3388902247f7d4 100644
--- a/third_party/WebKit/Source/core/editing/EditingUtilities.cpp
+++ b/third_party/WebKit/Source/core/editing/EditingUtilities.cpp
@@ -2159,4 +2159,47 @@ InputEvent::EventIsComposing isComposingFromCommand(
   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())

[Xiaocheng, 2017/01/06 02:24:53]

We currently don't check this.

Why do we need to cancel subsequent processing when the target node is removed?

[chongz, 2017/01/09 23:42:48]

We currently check |isConnected()| in
|Editor::deleteSelectionAfterDraggingWithEvents()| and
|Editor::replaceSelectionAfterDraggingWithEvents()| but not other places, but I
think we should do the same check for all 'beforeinput' to keep consistence.

See discussion with yosin@:
https://codereview.chromium.org/2288913002/#msg21

[Xiaocheng, 2017/01/10 03:05:11]

Seems reasonable... As the event target is the editing host, if it gets removed,
no more operation can be done.

+    return false;
+  return result == DispatchEventResult::NotCanceled;
+}
+
 }  // namespace blink