Mac: implement drag-and-drop of URLs to tabs/tab strip.

chrome/browser/cocoa/tab_strip_view.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/tab_strip_view.h"
 
 #include "base/logging.h"
 
 @implementation TabStripView
 
 @synthesize newTabButton = newTabButton_;
 
 - (id)initWithFrame:(NSRect)frame {
   self = [super initWithFrame:frame];
   if (self) {
     // Set lastMouseUp_ = -1000.0 so that timestamp-lastMouseUp_ is big unless
     // lastMouseUp_ has been reset.
     lastMouseUp_ = -1000.0;
+
+    // Register to be an URL drop target.
+    dropHandler_.reset([[URLDropTargetHandler alloc] initWithView:self]);
   }
   return self;
 }
 
 - (void)drawRect:(NSRect)rect {
   NSRect boundsRect = [self bounds];
   NSRect borderRect, contentRect;
   NSDivideRect(boundsRect, &borderRect, &contentRect, 1, NSMinYEdge);
   [[NSColor colorWithCalibratedWhite:0.0 alpha:0.2] set];
 
@@ skipping 36 matching lines @@
             performSelector:@selector(_shouldMiniaturizeOnDoubleClick)])
       [[self window] performMiniaturize:self];
   } else {
     [super mouseUp:event];
   }
 
   // If clickCount is 0, the drag threshold was passed.
   lastMouseUp_ = (clickCount == 1) ? timestamp : -1000.0;
 }
 
+// Required by |URLDropTargetHandler|.
+- (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)sender {
+  return [dropHandler_ draggingEntered:sender];
+}
+
+// Required by |URLDropTargetHandler|.
+- (NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)sender {
+  return [dropHandler_ draggingUpdated:sender];
+}
+
+// Required by |URLDropTargetHandler|.
+- (void)draggingExited:(id<NSDraggingInfo>)sender {
+  return [dropHandler_ draggingExited:sender];
+}
+
+// Required by |URLDropTargetHandler|.
+- (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {
+  return [dropHandler_ performDragOperation:sender];
+}
+
 @end