Media Controls: Fix time updates when dragging from track not scrubber

third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 78 matching lines @@
 
 bool SliderThumbElement::matchesReadWritePseudoClass() const {
   return hostInput() && hostInput()->matchesReadWritePseudoClass();
 }
 
 Node* SliderThumbElement::focusDelegate() {
   return hostInput();
 }
 
 void SliderThumbElement::dragFrom(const LayoutPoint& point) {
+  // Call setPositionFromPoint before startDragging, since this initial position
+  // change is due to the mousedown on track that precedes dragging (mousemove).
+  setPositionFromPoint(point);
   startDragging();
-  setPositionFromPoint(point);
 }
 
 void SliderThumbElement::setPositionFromPoint(const LayoutPoint& point) {
   HTMLInputElement* input(hostInput());
   Element* trackElement = input->userAgentShadowRoot()->getElementById(
       ShadowElementNames::sliderTrack());
 
   if (!input->layoutObject() || !layoutBox() || !trackElement->layoutBox())
     return;
 
@@ skipping 337 matching lines @@
   updateTouchEventHandlerRegistry();
   HTMLElement::didMoveToNewDocument(oldDocument);
 }
 
 void SliderContainerElement::removeAllEventListeners() {
   Node::removeAllEventListeners();
   m_hasTouchEventHandler = false;
 }
 
 }  // namespace blink