Add detached mode plumbing

chrome/browser/ui/cocoa/browser_window_controller_private.mm

Index: chrome/browser/ui/cocoa/browser_window_controller_private.mm
diff --git a/chrome/browser/ui/cocoa/browser_window_controller_private.mm b/chrome/browser/ui/cocoa/browser_window_controller_private.mm
index ef42630bf533ac8c320cc112950f82b722b4ec64..fbd7214e0f6274f8178cdd5956bfd3f07f9c092e 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller_private.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller_private.mm
@@ -908,6 +908,11 @@ willPositionSheet:(NSWindow*)sheet
   DCHECK(base::mac::IsOSLionOrLater());
   if (FramedBrowserWindow* framedBrowserWindow =
           base::mac::ObjCCast<FramedBrowserWindow>([self window])) {
+    if (WebContents* contents = [self webContents]) {
+      if (RenderWidgetHostView* rwhv = contents->GetRenderWidgetHostView()) {
+        detachedModeWindow_.reset(rwhv->CreateDetachedModeWindow());
+      }
+    }
     [framedBrowserWindow toggleSystemFullScreen];
   }
 }
@@ -918,6 +923,8 @@ willPositionSheet:(NSWindow*)sheet
           base::mac::ObjCCast<FramedBrowserWindow>([self window])) {
     [framedBrowserWindow toggleSystemFullScreen];
   }
+  [detachedModeWindow_ close];
+  detachedModeWindow_.reset();
 }
 
 - (NSRect)fullscreenButtonFrame {
@@ -1189,6 +1196,10 @@ willPositionSheet:(NSWindow*)sheet
 
   NSArray* customWindows =
       [fullscreenTransition_ customWindowsForFullScreenTransition];
+
+  if (detachedModeWindow_)
+    customWindows = [customWindows arrayByAddingObject:detachedModeWindow_];
+
   isUsingCustomAnimation_ = customWindows != nil;
   return customWindows;
 }