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

ui/aura_shell/drag_drop_controller.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/message_loop.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/window_drag_drop_delegate.h"
 #include "ui/aura/desktop.h"
@@ skipping 37 matching lines @@
       drag_drop_in_progress_(false),
       should_block_during_drag_drop_(true) {
   Shell::GetInstance()->AddDesktopEventFilter(this);
 }
 
 DragDropController::~DragDropController() {
   Shell::GetInstance()->RemoveDesktopEventFilter(this);
   Cleanup();
 }
 
-void DragDropController::StartDragAndDrop(const ui::OSExchangeData& data,
+int DragDropController::StartDragAndDrop(const ui::OSExchangeData& data,
                                           int operation) {
   DCHECK(!drag_drop_in_progress_);
   aura::Window* capture_window = Desktop::GetInstance()->capture_window();
   if (capture_window)
     Desktop::GetInstance()->ReleaseCapture(capture_window);
   drag_drop_in_progress_ = true;
 
   drag_data_ = &data;
   drag_operation_ = operation;
   gfx::Point location = Desktop::GetInstance()->last_mouse_location();
   const ui::OSExchangeDataProviderAura& provider =
       static_cast<const ui::OSExchangeDataProviderAura&>(data.provider());
 
   drag_image_.reset(new DragImageView);
   drag_image_->SetImage(provider.drag_image());
   drag_image_->SetScreenBounds(gfx::Rect(location.Add(kDragDropWidgetOffset),
       drag_image_->GetPreferredSize()));
   drag_image_->SetWidgetVisible(true);
 
-  dragged_window_ = Desktop::GetInstance()->GetEventHandlerForPoint(location);
+  dragged_window_ = NULL;
 
   if (should_block_during_drag_drop_) {
     MessageLoopForUI::current()->RunWithDispatcher(
         Desktop::GetInstance()->GetDispatcher());
   }
+  return drag_operation_;
 }
 
 void DragDropController::DragUpdate(aura::Window* target,
                                     const aura::MouseEvent& event) {
   aura::WindowDragDropDelegate* delegate = NULL;
   if (target != dragged_window_) {
     if ((delegate = GetDragDropDelegate(dragged_window_)))
       delegate->OnDragExited();
     dragged_window_ = target;
     if ((delegate = GetDragDropDelegate(dragged_window_))) {
       aura::DropTargetEvent e(*drag_data_, event.location(), drag_operation_);
-      if (delegate->CanDrop(e))
-        delegate->OnDragEntered(e);
+      delegate->OnDragEntered(e);
     }
   } else {
     if ((delegate = GetDragDropDelegate(dragged_window_))) {
       aura::DropTargetEvent e(*drag_data_, event.location(), drag_operation_);
-      delegate->OnDragUpdated(e);
-      // TODO(varunjain): uncomment the following lines when cursor issue with
-      // X for tests is fixed.
-      // gfx::NativeCursor cursor = (op == ui::DragDropTypes::DRAG_NONE)?
-      //     aura::kCursorMove : aura::kCursorHand;
-      // Desktop::GetInstance()->SetCursor(cursor);
+      int op = delegate->OnDragUpdated(e);
+       gfx::NativeCursor cursor = (op == ui::DragDropTypes::DRAG_NONE)?
+           aura::kCursorMove : aura::kCursorHand;
+       Desktop::GetInstance()->SetCursor(cursor);
     }
   }
 
   DCHECK(drag_image_.get());
   if (drag_image_->IsVisible()) {
     drag_image_->SetScreenPosition(Desktop::GetInstance()->
         last_mouse_location().Add(kDragDropWidgetOffset));
   }
 }
 
 void DragDropController::Drop(aura::Window* target,
                               const aura::MouseEvent& event) {
   aura::WindowDragDropDelegate* delegate = NULL;
   DCHECK(target == dragged_window_);
   if ((delegate = GetDragDropDelegate(dragged_window_))) {
     aura::DropTargetEvent e(*drag_data_, event.location(), drag_operation_);
-    if (delegate->CanDrop(e))
-      delegate->OnPerformDrop(e);
-    // TODO(varunjain): else Do drag widget flying back animation
+    drag_operation_ = delegate->OnPerformDrop(e);
+    // TODO(varunjain): if drag_op is 0, do drag widget flying back animation
   }
 
   Cleanup();
   if (should_block_during_drag_drop_)
     MessageLoop::current()->Quit();
 }
 
 void DragDropController::DragCancel() {
   // TODO(varunjain): Do drag widget flying back animation
   Cleanup();
+  drag_operation_ = 0;
   if (should_block_during_drag_drop_)
     MessageLoop::current()->Quit();
 }
 
+bool DragDropController::IsDragDropInProgress() {
+  return drag_drop_in_progress_;
+}
+
 bool DragDropController::PreHandleKeyEvent(aura::Window* target,
                                            aura::KeyEvent* event) {
   return false;
 }
 
 bool DragDropController::PreHandleMouseEvent(aura::Window* target,
                                              aura::MouseEvent* event) {
   if (!drag_drop_in_progress_)
     return false;
   switch (event->type()) {
@@ skipping 18 matching lines @@
     aura::TouchEvent* event) {
   return ui::TOUCH_STATUS_UNKNOWN;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // DragDropController, private:
 
 void DragDropController::Cleanup() {
   drag_image_.reset();
   drag_data_ = NULL;
-  drag_operation_ = 0;
   drag_drop_in_progress_ = false;
 }
 
 }  // namespace internal
 }  // namespace aura_shell