MacViews: Implement Tab Dragging

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 1c9560f2e8834aeb19225abd760819145854b361..75f7367be5e9e6c50a530c5d07840cf56470b199 100644
--- a/ui/views/cocoa/bridged_native_widget.mm
+++ b/ui/views/cocoa/bridged_native_widget.mm
@@ -25,6 +25,7 @@
 #import "ui/gfx/mac/nswindow_frame_controls.h"
 #import "ui/views/cocoa/bridged_content_view.h"
 #import "ui/views/cocoa/cocoa_mouse_capture.h"
+#import "ui/views/cocoa/cocoa_window_move_loop.h"
 #include "ui/views/cocoa/tooltip_manager_mac.h"
 #import "ui/views/cocoa/views_nswindow_delegate.h"
 #import "ui/views/cocoa/widget_owner_nswindow_adapter.h"
@@ -615,6 +616,61 @@ bool BridgedNativeWidget::HasCapture() {
   return mouse_capture_ && mouse_capture_->IsActive();
 }
 
+Widget::MoveLoopResult BridgedNativeWidget::RunMoveLoop(
+      const gfx::Vector2d& drag_offset) {
+  DCHECK(!HasCapture());
+  DCHECK(!window_move_loop_);
+
+  // First, position the window in the right place. The point |drag_offset|
+  // away from the top-left corner needs to be positioned under the mouse.
+  gfx::Point mouse_in_screen =
+      display::Screen::GetScreen()->GetCursorScreenPoint();
+
+  // A window can't be moved vertically up out of the work area. Treat this case
+  // as if the mouse location is at the point it would be when the window first
+  // stopped moving. That is, vertically down such that the top edge of the
+  // window touches the menubar (or top of the screen in a dual-screen setup).
+  // Note on Mac we can assume that the y-coordinate of the work area origin is
+  // the bottom of the menu bar and not the Dock which doesn't affect window
+  // movement, but can reduce the work area on the bottom, left and right.
+  const display::Display display =
+      display::Screen::GetScreen()->GetDisplayNearestPoint(mouse_in_screen);
+  const int min_y = display.work_area().y() + drag_offset.y();
+  if (mouse_in_screen.y() < min_y)
+    mouse_in_screen.set_y(min_y);
+
+  gfx::Rect frame = gfx::ScreenRectFromNSRect([window_ frame]);
+  frame.set_x(mouse_in_screen.x() - drag_offset.x());
+  frame.set_y(mouse_in_screen.y() - drag_offset.y());
+  DCHECK_GE(frame.y(), display.work_area().y());
+
+  // After setting the frame to correct the initial offset, the drag controller
+  // may immediately want to quit when it's notified of the new bounds. So the
+  // MoveLoop must be set up before the call to setFrame.
+  window_move_loop_.reset(new CocoaWindowMoveLoop(this, mouse_in_screen));
+
+  const NSRect ns_frame = gfx::ScreenRectToNSRect(frame);
+  [window_ setFrame:ns_frame display:NO animate:NO];
+
+  // Setting the frame will call OnWidgetBoundsChanged(), which could result in
+  // a call to EndMoveLoop().
+  if (!window_move_loop_)
+    return Widget::MOVE_LOOP_SUCCESSFUL;
+
+  return window_move_loop_->Run();
+
+  // |this| may be destroyed during the RunLoop, causing it to exit early.
+  // Even if that doesn't happen, CocoaWindowMoveLoop will clean itself up by
+  // calling EndMoveLoop(). So window_move_loop_ will always be null before the
+  // function returns. But don't DCHECK since |this| might not be valid.
+}
+
+void BridgedNativeWidget::EndMoveLoop() {
+  DCHECK(window_move_loop_);
+  window_move_loop_->End();
+  window_move_loop_.reset();
+}
+
 void BridgedNativeWidget::SetNativeWindowProperty(const char* name,
                                                   void* value) {
   NSString* key = [NSString stringWithUTF8String:name];
@@ -733,6 +789,10 @@ void BridgedNativeWidget::OnSizeChanged() {
     [bridged_view_ updateWindowMask];
 }
 
+void BridgedNativeWidget::OnPositionChanged() {
+  native_widget_mac_->GetWidget()->OnNativeWidgetMove();
+}
+
 void BridgedNativeWidget::OnVisibilityChanged() {
   OnVisibilityChangedTo([window_ isVisible]);
 }