Make drag and drop work on webpage. Also slightly modify drag drop workflow.

ui/aura_shell/drag_drop_controller_unittest.cc

 // Copyright (c) 2011 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 "ui/aura_shell/drag_drop_controller.h"
 
 #include "base/location.h"
 #include "base/utf_string_conversions.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/desktop.h"
@@ skipping 101 matching lines @@
     drop_received_ = false;
     drag_string_.clear();
   }
 
   bool drag_start_received_;
   int num_drag_updates_;
   bool drop_received_;
   string16 drag_string_;
 
  private:
-  void StartDragAndDrop(const ui::OSExchangeData& data,
-                        int operation) OVERRIDE {
-    DragDropController::StartDragAndDrop(data, operation);
+  int StartDragAndDrop(const ui::OSExchangeData& data,
+                       int operation) OVERRIDE {
     drag_start_received_ = true;
     data.GetString(&drag_string_);
+    return DragDropController::StartDragAndDrop(data, operation);
   }
 
   void DragUpdate(aura::Window* target,
                   const aura::MouseEvent& event) OVERRIDE {
     DragDropController::DragUpdate(target, event);
     num_drag_updates_++;
   }
 
   void Drop(aura::Window* target, const aura::MouseEvent& event) OVERRIDE {
     DragDropController::Drop(target, event);
@@ skipping 214 matching lines @@
   EXPECT_EQ(1, drag_view1->num_drag_enters_);
   int num_expected_updates = drag_view1->bounds().width() -
       drag_view1->bounds().CenterPoint().x() - 2;
   EXPECT_EQ(num_expected_updates - drag_view1->HorizontalDragThreshold(),
       drag_view1->num_drag_updates_);
   EXPECT_EQ(0, drag_view1->num_drops_);
   EXPECT_EQ(1, drag_view1->num_drag_exits_);
   EXPECT_TRUE(drag_view1->drag_done_received_);
 
   EXPECT_EQ(1, drag_view2->num_drag_enters_);
-  num_expected_updates = num_drags - num_expected_updates - 2;
+  num_expected_updates = num_drags - num_expected_updates - 1;
   EXPECT_EQ(num_expected_updates, drag_view2->num_drag_updates_);
   EXPECT_EQ(1, drag_view2->num_drops_);
   EXPECT_EQ(0, drag_view2->num_drag_exits_);
   EXPECT_FALSE(drag_view2->drag_done_received_);
   delete widget1;
   delete widget2;
 }
 
 TEST_F(DragDropControllerTest, ViewRemovedWhileInDragDropTest) {
   views::Widget* widget = CreateNewWidget();
@@ skipping 45 matching lines @@
   EXPECT_EQ(num_drags_1 - 1 - drag_view->VerticalDragThreshold(),
       drag_view->num_drag_updates_);
   EXPECT_EQ(0, drag_view->num_drops_);
   EXPECT_EQ(0, drag_view->num_drag_exits_);
   EXPECT_TRUE(drag_view->drag_done_received_);
   delete widget;
 }
 
 }  // namespace test
 }  // namespace aura