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

chrome/browser/cocoa/tab_window_controller.mm

 // Copyright (c) 2009 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/cocoa/tab_window_controller.h"
 
 #include "base/logging.h"
 #import "chrome/browser/cocoa/tab_strip_view.h"
 
 @interface TabWindowController(PRIVATE)
 - (void)setUseOverlay:(BOOL)useOverlay;
 @end
 
 @implementation TabWindowController
 @synthesize tabStripView = tabStripView_;
 @synthesize tabContentArea = tabContentArea_;
 
+- (id)initWithWindow:(NSWindow *)window {
+  if ((self = [super initWithWindow:window]) != nil) {
+    lockedTabs_.reset([[NSMutableSet alloc] initWithCapacity:10]);
+  }
+  return self;
+}
+
 - (void)windowDidLoad {
   if ([self isNormalWindow]) {
     // Place the tab bar above the content box and add it to the view hierarchy
     // as a sibling of the content view so it can overlap with the window frame.
     NSRect tabFrame = [tabContentArea_ frame];
     tabFrame.origin = NSMakePoint(0, NSMaxY(tabFrame));
     tabFrame.size.height = NSHeight([tabStripView_ frame]);
     [tabStripView_ setFrame:tabFrame];
     [[[[self window] contentView] superview] addSubview:tabStripView_];
   } else {
@@ skipping 141 matching lines @@
   NOTIMPLEMENTED();
   return @"";
 }
 
 - (BOOL)isNormalWindow {
   // subclass must implement
   NOTIMPLEMENTED();
   return YES;
 }
 
+- (BOOL)isTabDraggable:(NSView*)tabView {
+  return ![lockedTabs_ containsObject:tabView];
+}
+
+- (void)setTab:(NSView*)tabView isDraggable:(BOOL)draggable {
+  if (draggable)
+    [lockedTabs_ removeObject:tabView];
+  else
+    [lockedTabs_ addObject:tabView];
+}
+
 @end