Add support for constrained windows on os x, based on Avi's GTMWindowSheetController.

chrome/browser/cocoa/tab_window_controller.h

Index: chrome/browser/cocoa/tab_window_controller.h
diff --git a/chrome/browser/cocoa/tab_window_controller.h b/chrome/browser/cocoa/tab_window_controller.h
index 46928bd31fec55f42870dfdbff4f2fdfdd881b9c..4c0f07ac6c8315720743341de1e644c94eeb85d5 100644
--- a/chrome/browser/cocoa/tab_window_controller.h
+++ b/chrome/browser/cocoa/tab_window_controller.h
@@ -20,6 +20,8 @@
 
 #import <Cocoa/Cocoa.h>
 
+#include "base/scoped_nsobject.h"
+
 @class TabStripView;
 @class TabView;
 
@@ -31,6 +33,7 @@
   NSView* cachedContentView_;  // Used during dragging for identifying which
                                // view is the proper content area in the overlay
                                // (weak)
+  scoped_nsobject<NSMutableSet> lockedTabs_;
 }
 @property(readonly, nonatomic) TabStripView* tabStripView;
 @property(readonly, nonatomic) NSView* tabContentArea;
@@ -99,6 +102,8 @@
 // default implementation returns YES.
 - (BOOL)isNormalWindow;
 
+- (BOOL)isTabDraggable:(NSView*)tabView;
+- (void)setTab:(NSView*)tabView isDraggable:(BOOL)draggable;
 
 @end