MacViews: Implemented Drag & Drop

ui/views/cocoa/bridged_native_widget.mm

Index: ui/views/cocoa/bridged_native_widget.mm
diff --git a/ui/views/cocoa/bridged_native_widget.mm b/ui/views/cocoa/bridged_native_widget.mm
index da6acf2f6a6058fe3d52ded46b29a8c893c4e8c6..24b8ff6b4410849f2d82bcb3b0a91ab98f5b4914 100644
--- a/ui/views/cocoa/bridged_native_widget.mm
+++ b/ui/views/cocoa/bridged_native_widget.mm
@@ -24,6 +24,7 @@
 #import "ui/gfx/mac/coordinate_conversion.h"
 #import "ui/gfx/mac/nswindow_frame_controls.h"
 #import "ui/views/cocoa/bridged_content_view.h"
+#import "ui/views/cocoa/drag_drop_client_mac.h"
 #import "ui/views/cocoa/cocoa_mouse_capture.h"
 #include "ui/views/cocoa/tooltip_manager_mac.h"
 #import "ui/views/cocoa/views_nswindow_delegate.h"
@@ -463,6 +464,7 @@ void BridgedNativeWidget::Init(base::scoped_nsobject<NSWindow> window,
   // native on Mac, so nothing should ever want one in Widget form.
   DCHECK_NE(params.type, Widget::InitParams::TYPE_TOOLTIP);
   tooltip_manager_.reset(new TooltipManagerMac(this));
+  drag_drop_client_.reset(new DragDropClientMac(this));
 }
 
 void BridgedNativeWidget::SetFocusManager(FocusManager* focus_manager) {
@@ -527,6 +529,8 @@ void BridgedNativeWidget::SetRootView(views::View* view) {
 
   if (view) {
     bridged_view_.reset([[BridgedContentView alloc] initWithView:view]);
+    drag_drop_client_->SetRootView(view);
+
     // Objective C initializers can return nil. However, if |view| is non-NULL
     // this should be treated as an error and caught early.
     CHECK(bridged_view_);