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

chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <limits>
 #include <string>
@@ skipping 19 matching lines @@
 #include "chrome/browser/tabs/tab_strip_selection_model.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_navigator.h"
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 #import "chrome/browser/ui/cocoa/constrained_window_mac.h"
 #import "chrome/browser/ui/cocoa/image_button_cell.h"
 #import "chrome/browser/ui/cocoa/new_tab_button.h"
 #import "chrome/browser/ui/cocoa/profile_menu_button.h"
 #import "chrome/browser/ui/cocoa/tab_contents/favicon_util.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_controller.h"
+#import "chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_model_observer_bridge.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_view.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_view.h"
 #import "chrome/browser/ui/cocoa/tabs/throbber_view.h"
 #import "chrome/browser/ui/cocoa/tracking_area.h"
 #include "chrome/browser/ui/find_bar/find_bar.h"
 #include "chrome/browser/ui/find_bar/find_bar_controller.h"
 #include "chrome/browser/ui/find_bar/find_tab_helper.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
 #include "chrome/browser/ui/tabs/tab_menu_model.h"
@@ skipping 302 matching lines @@
           delegate:(id<TabStripControllerDelegate>)delegate {
   DCHECK(view && switchView && browser && delegate);
   if ((self = [super init])) {
     tabStripView_.reset([view retain]);
     switchView_ = switchView;
     browser_ = browser;
     tabStripModel_ = browser_->tabstrip_model();
     hoverTabSelector_.reset(new HoverTabSelector(tabStripModel_));
     delegate_ = delegate;
     bridge_.reset(new TabStripModelObserverBridge(tabStripModel_, self));
+    dragController_.reset(
+        [[TabStripDragController alloc] initWithTabStripController:self]);
     tabContentsArray_.reset([[NSMutableArray alloc] init]);
     tabArray_.reset([[NSMutableArray alloc] init]);
     NSWindow* browserWindow = [view window];
 
     // Important note: any non-tab subviews not added to |permanentSubviews_|
     // (see |-addSubviewToPermanentList:|) will be wiped out.
     permanentSubviews_.reset([[NSMutableArray alloc] init]);
 
     defaultFavicon_.reset(
         [app::mac::GetCachedImageWithName(@"nav.pdf") retain]);
@@ skipping 432 matching lines @@
   return tabStripModel_->IsContextMenuCommandEnabled(index, command) ? YES : NO;
 }
 
 // Returns a context menu model for a given controller. Caller owns the result.
 - (ui::SimpleMenuModel*)contextMenuModelForController:(TabController*)controller
     menuDelegate:(ui::SimpleMenuModel::Delegate*)delegate {
   int index = [self modelIndexForTabView:[controller view]];
   return new TabMenuModel(delegate, tabStripModel_, index);
 }
 
+// Returns a weak reference to the controller that manages dragging of tabs.
+- (id<TabDraggingEventTarget>)dragController {
+  return dragController_.get();
+}
+
 - (void)insertPlaceholderForTab:(TabView*)tab
                           frame:(NSRect)frame
                   yStretchiness:(CGFloat)yStretchiness {
   placeholderTab_ = tab;
   placeholderFrame_ = frame;
   placeholderStretchiness_ = yStretchiness;
   [self layoutTabsWithAnimation:initialLayoutComplete_ regenerateSubviews:NO];
 }
 
 - (BOOL)isDragSessionActive {
@@ skipping 1304 matching lines @@
   }
 
   std::string profileName = browser_->profile()->GetPrefs()->GetString(
       prefs::kGoogleServicesUsername);
   [profileMenuButton_ setProfileDisplayName:
       [NSString stringWithUTF8String:profileName.c_str()]];
   [profileMenuButton_ setHidden:NO];
 }
 
 @end