[Mac] Refactor the logic of tab dragging out of TabView and into a new helper.

chrome/browser/ui/cocoa/tabs/tab_view.h

Index: chrome/browser/ui/cocoa/tabs/tab_view.h
diff --git a/chrome/browser/ui/cocoa/tabs/tab_view.h b/chrome/browser/ui/cocoa/tabs/tab_view.h
index 17eb1738110b81d0533613974a1b02f3325ad9ef..72d434a6499d5753ecddf872b4961e94184b3b11 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_view.h
+++ b/chrome/browser/ui/cocoa/tabs/tab_view.h
@@ -9,8 +9,6 @@
 #import <Cocoa/Cocoa.h>
 #include <ApplicationServices/ApplicationServices.h>
 
-#include <map>
-
 #include "base/memory/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/background_gradient_view.h"
 #import "chrome/browser/ui/cocoa/hover_close_button.h"
@@ -66,34 +64,9 @@ enum AlertState {
 
   NSPoint hoverPoint_;  // Current location of hover in view coords.
 
-  // All following variables are valid for the duration of a drag.
-  // These are released on mouseUp:
-  BOOL moveWindowOnDrag_;  // Set if the only tab of a window is dragged.
-  BOOL tabWasDragged_;  // Has the tab been dragged?
-  BOOL draggingWithinTabStrip_;  // Did drag stay in the current tab strip?
-  BOOL chromeIsVisible_;
-
-  NSTimeInterval tearTime_;  // Time since tear happened
-  NSPoint tearOrigin_;  // Origin of the tear rect
-  NSPoint dragOrigin_;  // Origin point of the drag
-  // TODO(alcor): these references may need to be strong to avoid crashes
-  // due to JS closing windows
-  TabWindowController* sourceController_;  // weak. controller starting the drag
-  NSWindow* sourceWindow_;  // weak. The window starting the drag
-  NSRect sourceWindowFrame_;
-  NSRect sourceTabFrame_;
-
-  TabWindowController* draggedController_;  // weak. Controller being dragged.
-  NSWindow* dragWindow_;  // weak. The window being dragged
-  NSWindow* dragOverlay_;  // weak. The overlay being dragged
-  // Cache workspace IDs per-drag because computing them on 10.5 with
-  // CGWindowListCreateDescriptionFromArray is expensive.
-  // resetDragControllers clears this cache.
-  //
-  // TODO(davidben): When 10.5 becomes unsupported, remove this.
-  std::map<CGWindowID, int> workspaceIDCache_;
-
-  TabWindowController* targetController_;  // weak. Controller being targeted
+  // The location of the current mouseDown event in window coordinates.
+  NSPoint mouseDownPoint_;
+
   NSCellStateValue state_;
 }