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

chrome/browser/cocoa/tab_window_controller.mm

Index: chrome/browser/cocoa/tab_window_controller.mm
diff --git a/chrome/browser/cocoa/tab_window_controller.mm b/chrome/browser/cocoa/tab_window_controller.mm
index 34417a08f1bc6ac54fa9edf193097e6ba0825067..7684f13bdaf788a0be97b3380ca9734966588e79 100644
--- a/chrome/browser/cocoa/tab_window_controller.mm
+++ b/chrome/browser/cocoa/tab_window_controller.mm
@@ -15,6 +15,13 @@
 @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
@@ -176,4 +183,15 @@
   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