Use the screen info's scale factor to scale the drag image

third_party/WebKit/Source/web/DragClientImpl.cpp

 /*
  * Copyright (C) 2009 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "web/DragClientImpl.h"
 
 #include "core/clipboard/DataObject.h"
 #include "core/clipboard/DataTransfer.h"
 #include "core/frame/LocalFrame.h"
+#include "core/page/ChromeClient.h"

[jbroman, 2016/01/13 15:35:13]

nit: Why this include? You don't seem to have added a use of ChromeClient.

[oshima, 2016/01/13 18:19:43]

m_webView->client() returns ChromeClient

[dcheng, 2016/01/13 18:20:53]

This returns WebViewClient, not ChromeClient.

 #include "platform/DragImage.h"
 #include "platform/geometry/IntSize.h"
 #include "public/platform/WebCommon.h"
 #include "public/platform/WebDragData.h"
 #include "public/platform/WebImage.h"
 #include "public/platform/WebPoint.h"
 #include "public/web/WebDragOperation.h"
 #include "public/web/WebViewClient.h"
 #include "web/WebViewImpl.h"
 #include "wtf/Assertions.h"
@@ skipping 16 matching lines @@
     RefPtrWillBeRawPtr<LocalFrame> frameProtector(frame);
 
     WebDragData dragData = dataTransfer->dataObject()->toWebDragData();
     WebDragOperationsMask dragOperationMask = static_cast<WebDragOperationsMask>(dataTransfer->sourceOperation());
     WebImage image;
     IntSize offsetSize(eventPos - dragImageOrigin);
     WebPoint offsetPoint(offsetSize.width(), offsetSize.height());
 
     if (dragImage) {
         float resolutionScale = dragImage->resolutionScale();
-        if (m_webView->deviceScaleFactor() != resolutionScale) {
+        float deviceScaleFactor =
+            m_webView->client()->screenInfo().deviceScaleFactor;
+        if (deviceScaleFactor != resolutionScale) {
             ASSERT(resolutionScale > 0);
-            float scale = m_webView->deviceScaleFactor() / resolutionScale;
+            float scale = deviceScaleFactor / resolutionScale;
             dragImage->scale(scale, scale);
         }
         image = dragImage->bitmap();
     }
 
     m_webView->startDragging(frame, dragData, dragOperationMask, image, offsetPoint);
 }
 
 } // namespace blink