WebDragSource: Added a guard for null [contentView_ window]

chrome/browser/ui/cocoa/web_drag_source.mm

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/web_drag_source.h"
 
 #include "app/mac/nsimage_cache.h"
 #include "base/file_path.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
@@ skipping 239 matching lines @@
           slideBack:YES];
 }
 
 - (void)endDragAt:(NSPoint)screenPoint
         operation:(NSDragOperation)operation {
   RenderViewHost* rvh = [contentsView_ tabContents]->render_view_host();
   if (rvh) {
     rvh->DragSourceSystemDragEnded();
 
     // Convert |screenPoint| to view coordinates and flip it.
-    NSPoint localPoint = [self convertScreenPoint:screenPoint];
+    NSPoint localPoint = NSMakePoint(0, 0);
+    if ([contentsView_ window])
+      localPoint = [self convertScreenPoint:screenPoint];
     NSRect viewFrame = [contentsView_ frame];
     localPoint.y = viewFrame.size.height - localPoint.y;
     // Flip |screenPoint|.
     NSRect screenFrame = [[[contentsView_ window] screen] frame];
     screenPoint.y = screenFrame.size.height - screenPoint.y;
 
     rvh->DragSourceEndedAt(localPoint.x, localPoint.y,
                            screenPoint.x, screenPoint.y,
                            static_cast<WebKit::WebDragOperation>(operation));
   }
 
   // Make sure the pasteboard owner isn't us.
   [pasteboard_ declareTypes:[NSArray array] owner:nil];
 }
 
 - (void)moveDragTo:(NSPoint)screenPoint {
   RenderViewHost* rvh = [contentsView_ tabContents]->render_view_host();
   if (rvh) {
     // Convert |screenPoint| to view coordinates and flip it.
-    NSPoint localPoint = [self convertScreenPoint:screenPoint];
+    NSPoint localPoint = NSMakePoint(0, 0);
+    if ([contentsView_ window])
+      localPoint = [self convertScreenPoint:screenPoint];
     NSRect viewFrame = [contentsView_ frame];
     localPoint.y = viewFrame.size.height - localPoint.y;
     // Flip |screenPoint|.
     NSRect screenFrame = [[[contentsView_ window] screen] frame];
     screenPoint.y = screenFrame.size.height - screenPoint.y;
 
     rvh->DragSourceMovedTo(localPoint.x, localPoint.y,
                            screenPoint.x, screenPoint.y);
   }
 }
@@ skipping 112 matching lines @@
 
 - (NSImage*)dragImage {
   if (dragImage_)
     return dragImage_;
 
   // Default to returning a generic image.
   return app::mac::GetCachedImageWithName(@"nav.pdf");
 }
 
 @end  // @implementation WebDragSource (Private)