Pass result of blockage across content API when new tab blocked.

chrome/browser/ui/views/tabs/tab_drag_controller.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/ui/views/tabs/tab_drag_controller.h"
 
 #include <math.h>
 #include <set>
 
 #include "base/callback.h"
@@ skipping 539 matching lines @@
         drag_data_[i].original_delegate->NavigationStateChanged(source,
                                                                 changed_flags);
         break;
       }
     }
   }
   if (view_.get())
     view_->Update();
 }
 
-void TabDragController::AddNewContents(WebContents* source,
+bool TabDragController::AddNewContents(WebContents* source,
                                        WebContents* new_contents,
                                        WindowOpenDisposition disposition,
                                        const gfx::Rect& initial_pos,
                                        bool user_gesture) {
   DCHECK_NE(CURRENT_TAB, disposition);
 
   // Theoretically could be called while dragging if the page tries to
   // spawn a window. Route this message back to the browser in most cases.
   if (source_tab_drag_data()->original_delegate) {
-    source_tab_drag_data()->original_delegate->AddNewContents(
+    return source_tab_drag_data()->original_delegate->AddNewContents(
         source, new_contents, disposition, initial_pos, user_gesture);
   }
+  return true;
 }
 
 void TabDragController::LoadingStateChanged(WebContents* source) {
   // It would be nice to respond to this message by changing the
   // screen shot in the dragged tab.
   if (view_.get())
     view_->Update();
 }
 
 bool TabDragController::ShouldSuppressDialogs() {
@@ skipping 1398 matching lines @@
 gfx::Point TabDragController::GetWindowOffset(
     const gfx::Point& point_in_screen) {
   TabStrip* owning_tabstrip = (attached_tabstrip_ && detach_into_browser_) ?
       attached_tabstrip_ : source_tabstrip_;
   views::View* toplevel_view = owning_tabstrip->GetWidget()->GetContentsView();
 
   gfx::Point offset = point_in_screen;
   views::View::ConvertPointFromScreen(toplevel_view, &offset);
   return offset;
 }