Plumb the DragOperation through all the layers between the platform DnD code ...

chrome/browser/cocoa/web_drop_target.mm

 // Copyright (c) 2009 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/cocoa/web_drop_target.h"
 
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/renderer_host/render_view_host.h"
 #include "chrome/browser/tab_contents/tab_contents.h"
 #import "third_party/mozilla/include/NSPasteboard+Utils.h"
 #include "webkit/glue/webdropdata.h"
 #include "webkit/glue/window_open_disposition.h"
 
+using WebKit::WebDragOperationsMask;
+
 @implementation WebDropTarget
 
 // |contents| is the TabContents representing this tab, used to communicate
 // drag&drop messages to WebCore and handle navigation on a successful drop
 // (if necessary).
 - (id)initWithTabContents:(TabContents*)contents {
   if ((self = [super init])) {
     tabContents_ = contents;
   }
   return self;
 }
 
 // Call to set whether or not we should allow the drop. Takes effect the
 // next time |-draggingUpdated:| is called.
-- (void)setIsDropTarget:(BOOL)isDropTarget {
-  isDropTarget_ = isDropTarget;
+- (void)setCurrentOperation: (NSDragOperation)operation {
+  current_operation_ = operation;
 }
 
 // Given a point in window coordinates and a view in that window, return a
 // flipped point in the coordinate system of |view|.
 - (NSPoint)flipWindowPointToView:(const NSPoint&)windowPoint
                             view:(NSView*)view {
   DCHECK(view);
   NSPoint viewPoint =  [view convertPoint:windowPoint fromView:nil];
   NSRect viewFrame = [view frame];
   viewPoint.y = viewFrame.size.height - viewPoint.y;
@@ skipping 38 matching lines @@
 
   // Fill out a WebDropData from pasteboard.
   WebDropData data;
   [self populateWebDropData:&data fromPasteboard:[info draggingPasteboard]];
 
   // Create the appropriate mouse locations for WebCore. The draggingLocation
   // is in window coordinates. Both need to be flipped.
   NSPoint windowPoint = [info draggingLocation];
   NSPoint viewPoint = [self flipWindowPointToView:windowPoint view:view];
   NSPoint screenPoint = [self flipWindowPointToScreen:windowPoint view:view];
+  NSDragOperation mask = [info draggingSourceOperationMask];
   tabContents_->render_view_host()->DragTargetDragEnter(data,
       gfx::Point(viewPoint.x, viewPoint.y),
-      gfx::Point(screenPoint.x, screenPoint.y));
+      gfx::Point(screenPoint.x, screenPoint.y),
+      static_cast<WebDragOperationsMask>(mask));
 
-  isDropTarget_ = YES;
-
-  return NSDragOperationCopy;
+  // We won't know the true operation (whether the drag is allowed) until we
+  // hear back from the renderer. For now, be optimistic:
+  current_operation_ = NSDragOperationCopy;
+  return current_operation_;
 }
 
 - (void)draggingExited:(id<NSDraggingInfo>)info {
   DCHECK(currentRVH_);
   if (currentRVH_ != tabContents_->render_view_host())
     return;
 
   // Nothing to do in the interstitial case.
 
   tabContents_->render_view_host()->DragTargetDragLeave();
 }
 
 - (NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)info
                               view:(NSView*)view {
   DCHECK(currentRVH_);
   if (currentRVH_ != tabContents_->render_view_host())
     [self draggingEntered:info];
 
   if ([self onlyAllowsNavigation]) {
     if ([[info draggingPasteboard] containsURLData])
       return NSDragOperationCopy;
     return NSDragOperationNone;
   }
 
   // Create the appropriate mouse locations for WebCore. The draggingLocation
   // is in window coordinates.
   NSPoint windowPoint = [info draggingLocation];
   NSPoint viewPoint = [self flipWindowPointToView:windowPoint view:view];
   NSPoint screenPoint = [self flipWindowPointToScreen:windowPoint view:view];
+  NSDragOperation mask = [info draggingSourceOperationMask];
   tabContents_->render_view_host()->DragTargetDragOver(
       gfx::Point(viewPoint.x, viewPoint.y),
-      gfx::Point(screenPoint.x, screenPoint.y));
+      gfx::Point(screenPoint.x, screenPoint.y),
+      static_cast<WebDragOperationsMask>(mask));
 
-  if (!isDropTarget_)
-    return NSDragOperationNone;
-  return NSDragOperationCopy;
+  return current_operation_;
 }
 
 - (BOOL)performDragOperation:(id<NSDraggingInfo>)info
                               view:(NSView*)view {
   if (currentRVH_ != tabContents_->render_view_host())
     [self draggingEntered:info];
 
   // Check if we only allow navigation and navigate to a url on the pasteboard.
   if ([self onlyAllowsNavigation]) {
     NSPasteboard* pboard = [info draggingPasteboard];
@@ skipping 59 matching lines @@
   // Get HTML.
   if ([types containsObject:NSHTMLPboardType]) {
     data->text_html =
         base::SysNSStringToUTF16([pboard stringForType:NSHTMLPboardType]);
   }
 
   // TODO(pinkerton): Get files and file contents.
 }
 
 @end