First shot at implementing drag&drop for Aura

ui/aura/desktop.cc

Index: ui/aura/desktop.cc
diff --git a/ui/aura/desktop.cc b/ui/aura/desktop.cc
index 07edd119e56a49ef6959963163ca607618673427..d5e3c8c0af33906888c328cf43cec49c0de809ff 100644
--- a/ui/aura/desktop.cc
+++ b/ui/aura/desktop.cc
@@ -17,6 +17,7 @@
 #include "ui/aura/desktop_delegate.h"
 #include "ui/aura/desktop_host.h"
 #include "ui/aura/desktop_observer.h"
+#include "ui/aura/drag_drop_controller.h"
 #include "ui/aura/event.h"
 #include "ui/aura/event_filter.h"
 #include "ui/aura/focus_manager.h"
@@ -82,6 +83,10 @@ class DefaultDesktopDelegate : public DesktopDelegate {
     return NULL;
   }
 
+  virtual DragDropController* GetDragDropController() const OVERRIDE {
+    return NULL;
+  }
+
   Desktop* desktop_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultDesktopDelegate);
@@ -221,7 +226,8 @@ Desktop::Desktop()
       mouse_pressed_handler_(NULL),
       mouse_moved_handler_(NULL),
       focused_window_(NULL),
-      touch_event_handler_(NULL) {
+      touch_event_handler_(NULL),
+      drag_drop_in_progress_(false) {
   set_name("RootWindow");
   gfx::Screen::SetInstance(screen_);
   host_->SetDesktop(this);
@@ -296,6 +302,25 @@ bool Desktop::DispatchMouseEvent(MouseEvent* event) {
 
   last_mouse_location_ = event->location();
 
+  if (drag_drop_in_progress_) {
+    DCHECK(delegate_->GetDragDropController());
+    switch (event->type()) {
+      case ui::ET_MOUSE_DRAGGED:
+        delegate_->GetDragDropController()->DragUpdate(*event);
+        break;
+      case ui::ET_MOUSE_RELEASED:
+        delegate_->GetDragDropController()->Drop(*event);
+      case ui::ET_MOUSE_EXITED:
+        drag_drop_in_progress_ = false;
+        MessageLoop::current()->Quit();
+        break;
+      default:
+        NOTREACHED();
+        break;
+    }
+    return true;
+  }
+
   Window* target =
       mouse_pressed_handler_ ? mouse_pressed_handler_ : capture_window_;
   if (!target)
@@ -493,6 +518,17 @@ void Desktop::SetTransform(const ui::Transform& transform) {
     OnHostResized(host_->GetSize());
 }
 
+void Desktop::StartDragAndDrop(const ui::OSExchangeData& data, int operation) {
+  if (delegate_->GetDragDropController() && !drag_drop_in_progress_) {
+    if (capture_window_)
+      ReleaseCapture(capture_window_);
+    delegate_->GetDragDropController()->StartDragAndDrop(data, operation,
+        last_mouse_location_);
+    drag_drop_in_progress_ = true;
+    MessageLoopForUI::current()->RunWithDispatcher(host_.get());
+  }
+}
+
 void Desktop::HandleMouseMoved(const MouseEvent& event, Window* target) {
   if (target == mouse_moved_handler_)
     return;