[InputEvent] Support |deleteByDrag| and |insertFromDrop|

third_party/WebKit/Source/core/page/DragController.cpp

Index: third_party/WebKit/Source/core/page/DragController.cpp
diff --git a/third_party/WebKit/Source/core/page/DragController.cpp b/third_party/WebKit/Source/core/page/DragController.cpp
index c0a684f1d686859f59777949014ff1a06ba3a310..00a0bdab28d5abe61a88db14636e5f997feb49c2 100644
--- a/third_party/WebKit/Source/core/page/DragController.cpp
+++ b/third_party/WebKit/Source/core/page/DragController.cpp
@@ -92,6 +92,62 @@
 
 namespace blink {
 
+namespace {
+
+DataTransfer* createDraggingDataTransfer(DataTransferAccessPolicy policy, DragData* dragData)
+{
+    return DataTransfer::create(DataTransfer::DragAndDrop, policy, dragData->platformData());
+}
+
+enum class DragDropBeforeInputResult {
+    None,
+    DeleteOnly,
+    InsertOnly,
+    DeleteAndInsert,
+};
+
+DragDropBeforeInputResult dispatchDragDropBeforeInput(Element* dragTarget, Element* dropTarget, DragData* dragData, bool dragIsMove)
+{
+    LocalFrame* dragFrame = dragTarget->document().frame();
+    LocalFrame* dropFrame = dropTarget->document().frame();
+
+    // Handle DeleteByDrag.
+    bool shouldDelete = dragIsMove;
+    if (shouldDelete) {
+        DispatchEventResult dragBeforeInputResult = dispatchBeforeInputEditorCommand(dragTarget, InputEvent::InputType::DeleteByDrag, emptyString(), nullptr);
+        shouldDelete = dragBeforeInputResult == DispatchEventResult::NotCanceled;
+    }
+
+    // 'beforeinput' event handler may destroy frame.
+    if (dragFrame != dragTarget->document().frame() || dropFrame != dropTarget->document().frame())
+        return DragDropBeforeInputResult::None;
+
+    // Handle InsertFromDrop.
+    DataTransfer* dataTransfer = createDraggingDataTransfer(DataTransferReadable, dragData);
+    dataTransfer->setSourceOperation(dragData->draggingSourceOperationMask());
+    DispatchEventResult dropBeforeInputResult = dispatchBeforeInputDataTransfer(dropTarget, InputEvent::InputType::InsertFromDrop, dataTransfer, nullptr);
+    bool shouldInsert = dropBeforeInputResult == DispatchEventResult::NotCanceled;
+
+    // 'beforeinput' event handler may destroy frame.
+    if (dragFrame != dragTarget->document().frame() || dropFrame != dropTarget->document().frame())
+        return DragDropBeforeInputResult::None;
+
+    // 'beforeinput' event handler may remove element from document, editing commands won't modify disconnected elements.
+    shouldDelete = shouldDelete && dragTarget->isConnected();
+    shouldInsert = shouldInsert && dropTarget->isConnected();
+
+    // Generate dispatch result.
+    if (shouldDelete && shouldInsert)
+        return DragDropBeforeInputResult::DeleteAndInsert;
+    if (shouldDelete)
+        return DragDropBeforeInputResult::DeleteOnly;
+    if (shouldInsert)
+        return DragDropBeforeInputResult::InsertOnly;
+    return DragDropBeforeInputResult::None;
+}
+
+} // anonymous namespace
+
 const int DragController::DragIconRightInset = 7;
 const int DragController::DragIconBottomInset = 3;
 
@@ -124,11 +180,6 @@ static PlatformMouseEvent createMouseEvent(DragData* dragData)
         PlatformMouseEvent::RealOrIndistinguishable, monotonicallyIncreasingTime());
 }
 
-static DataTransfer* createDraggingDataTransfer(DataTransferAccessPolicy policy, DragData* dragData)
-{
-    return DataTransfer::create(DataTransfer::DragAndDrop, policy, dragData->platformData());
-}
-
 DragController::DragController(Page* page)
     : m_page(page)
     , m_documentUnderMouse(nullptr)
@@ -503,36 +554,59 @@ bool DragController::concludeEditDrag(DragData* dragData)
     if (!range)
         return false;
     ResourceFetcher* fetcher = range->ownerDocument().fetcher();
-    ResourceCacheValidationSuppressor validationSuppressor(fetcher);
-    if (dragIsMove(innerFrame->selection(), dragData) || dragCaret.isContentRichlyEditable()) {
-        bool chosePlainText = false;
-        DocumentFragment* fragment = documentFragmentFromDragData(dragData, innerFrame, range, true, chosePlainText);
-        if (!fragment)
-            return false;
+    ResourceCacheValidationSuppressor validationSuppressorr(fetcher);
 
-        if (dragIsMove(innerFrame->selection(), dragData)) {
-            // NSTextView behavior is to always smart delete on moving a selection,
-            // but only to smart insert if the selection granularity is word granularity.
-            bool smartDelete = innerFrame->editor().smartInsertDeleteEnabled();
-            bool smartInsert = smartDelete && innerFrame->selection().granularity() == WordGranularity && dragData->canSmartReplace();
-            innerFrame->editor().moveSelectionAfterDragging(fragment, dragCaret.base(), smartInsert, smartDelete);
-        } else {
+    LocalFrame* frameUnderMouse = m_documentUnderMouse->frame();
+    DCHECK(frameUnderMouse);
+    DragDropBeforeInputResult beforeInputResult = dispatchDragDropBeforeInput(innerFrame->editor().findEventTargetFromSelection(), element, dragData, dragIsMove(innerFrame->selection(), dragData));
+    // 'beforeinput' handler may destroy frame.
+    if (innerFrame->document()->frame() != innerFrame || m_documentUnderMouse->frame() != frameUnderMouse)
+        return false;
+
+    switch (beforeInputResult) {
+    case DragDropBeforeInputResult::None:
+    default:
+        return true;
+
+    case DragDropBeforeInputResult::DeleteOnly:
+        innerFrame->editor().deleteSelectionWithSmartDelete(innerFrame->editor().smartInsertDeleteEnabled(), InputEvent::InputType::DeleteByDrag);
+        break;
+
+    case DragDropBeforeInputResult::InsertOnly:
+        if (dragCaret.isContentRichlyEditable()) {
+            bool chosePlainText = false;
+            DocumentFragment* fragment = documentFragmentFromDragData(dragData, innerFrame, range, true, chosePlainText);
+            if (!fragment)
+                return false;
             if (setSelectionToDragCaret(innerFrame, dragCaret, range, point)) {
-                ASSERT(m_documentUnderMouse);
+                DCHECK(m_documentUnderMouse);
                 m_documentUnderMouse->frame()->editor().replaceSelectionAfterDragging(fragment, dragData->canSmartReplace(), chosePlainText);
             }
-        }
-    } else {
-        String text = dragData->asPlainText();
-        if (text.isEmpty())
-            return false;
+        } else {
+            String text = dragData->asPlainText();
+            if (text.isEmpty())
+                return false;
 
-        if (setSelectionToDragCaret(innerFrame, dragCaret, range, point)) {
-            const bool canSmartReplace = false;
-            const bool chosePlainText = true;
-            ASSERT(m_documentUnderMouse);
-            m_documentUnderMouse->frame()->editor().replaceSelectionAfterDragging(createFragmentFromText(EphemeralRange(range), text), canSmartReplace, chosePlainText);
+            if (setSelectionToDragCaret(innerFrame, dragCaret, range, point)) {
+                const bool canSmartReplace = false;
+                const bool chosePlainText = true;
+                DCHECK(m_documentUnderMouse);
+                m_documentUnderMouse->frame()->editor().replaceSelectionAfterDragging(createFragmentFromText(EphemeralRange(range), text), canSmartReplace, chosePlainText);
+            }
         }
+        break;
+
+    case DragDropBeforeInputResult::DeleteAndInsert:
+        bool chosePlainText = false;
+        DocumentFragment* fragment = documentFragmentFromDragData(dragData, innerFrame, range, true, chosePlainText);
+        if (!fragment)
+            return false;
+        // NSTextView behavior is to always smart delete on moving a selection,
+        // but only to smart insert if the selection granularity is word granularity.
+        bool smartDelete = innerFrame->editor().smartInsertDeleteEnabled();
+        bool smartInsert = smartDelete && innerFrame->selection().granularity() == WordGranularity && dragData->canSmartReplace();
+        innerFrame->editor().moveSelectionAfterDragging(fragment, dragCaret.base(), smartInsert, smartDelete);
+        break;
     }
 
     if (rootEditableElement) {