Remove some probably dead code in EventHandler::handleDrag.

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * 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.
@@ skipping 632 matching lines @@
     m_mouseDownMayStartAutoscroll = m_mouseDownMayStartSelect
         || (m_mousePressNode && m_mousePressNode->renderBox() && m_mousePressNode->renderBox()->canBeProgramaticallyScrolled());
 
     return swallowEvent;
 }
 
 bool EventHandler::handleMouseDraggedEvent(const MouseEventWithHitTestResults& event)
 {
     TRACE_EVENT0("blink", "EventHandler::handleMouseDraggedEvent");
 
-    if (!m_mousePressed)
+    if (!m_mousePressed || event.event().button() != LeftButton)

[Rick Byers, 2014/11/14 18:29:28]

You said this case is "probably dead".  Should we perhaps add an ASSERT to see
if we can catch anyone trying to do a drag without the left button being
pressed?  If there are any such cases, it could be a compat bug...

[dcheng, 2014/11/14 18:41:26]

The thing is, we always bailed out anyway if it wasn't a left button drag. The
check was just done in two different places before--once at the beginning
handleDrag(), and once after handleDrag() returned. The check has been
consolidated into one place.

The other possibility is someone passing in a MouseEvent that's not a MouseMoved
event. In that case, we would skip the HTML drag steps, but not skip the default
drag handling steps. It seems a bit silly to do that, so now, we go through the
same set of steps for both.

         return false;
 
     if (handleDrag(event, DragInitiator::Mouse))
         return true;
 
     Node* targetNode = event.innerNode();
-    if (event.event().button() != LeftButton || !targetNode)
+    if (!targetNode)
         return false;
 
     RenderObject* renderer = targetNode->renderer();
     if (!renderer) {
         Node* parent = NodeRenderingTraversal::parent(targetNode);
         if (!parent)
             return false;
 
         renderer = parent->renderer();
         if (!renderer || !renderer->isListBox())
@@ skipping 2531 matching lines @@
 bool EventHandler::handleDrag(const MouseEventWithHitTestResults& event, DragInitiator initiator)
 {
     ASSERT(event.event().type() == PlatformEvent::MouseMoved);
     // Callers must protect the reference to FrameView, since this function may dispatch DOM
     // events, causing page/FrameView to go away.
     ASSERT(m_frame);
     ASSERT(m_frame->view());
     if (!m_frame->page())
         return false;
 
-    // FIXME: Does this ever get hit??
-    if (event.event().button() != LeftButton || event.event().type() != PlatformEvent::MouseMoved) {
-        // If we allowed the other side of the bridge to handle a drag
-        // last time, then m_mousePressed might still be set. So we
-        // clear it now to make sure the next move after a drag
-        // doesn't look like a drag.
-        m_mousePressed = false;
-        return false;
-    }
-
     if (m_mouseDownMayStartDrag) {
         HitTestRequest request(HitTestRequest::ReadOnly);
         HitTestResult result(m_mouseDownPos);
         m_frame->contentRenderer()->hitTest(request, result);
         Node* node = result.innerNode();
         if (node) {
             DragController::SelectionDragPolicy selectionDragPolicy = event.event().timestamp() - m_mouseDownTimestamp < TextDragDelay
                 ? DragController::DelayedSelectionDragResolution
                 : DragController::ImmediateSelectionDragResolution;
             dragState().m_dragSrc = m_frame->page()->dragController().draggableNode(m_frame, node, m_mouseDownPos, selectionDragPolicy, dragState().m_dragType);
@@ skipping 634 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink