Cocoa: Support constrained windows for platform apps

chrome/browser/ui/cocoa/constrained_window_mac.h

Index: chrome/browser/ui/cocoa/constrained_window_mac.h
diff --git a/chrome/browser/ui/cocoa/constrained_window_mac.h b/chrome/browser/ui/cocoa/constrained_window_mac.h
index 50daeeda2f40d9d5981a1c86db2f49b5323f9eb9..c2b37967940afcdc837eed1fe2f3478bf1c19513 100644
--- a/chrome/browser/ui/cocoa/constrained_window_mac.h
+++ b/chrome/browser/ui/cocoa/constrained_window_mac.h
@@ -12,12 +12,28 @@
 #include "base/memory/scoped_nsobject.h"
 #include "chrome/browser/ui/constrained_window.h"
 
-@class BrowserWindowController;
+class ConstrainedWindowMac;
 @class GTMWindowSheetController;
 @class NSView;
 @class NSWindow;
 class TabContents;
 
+// Window controllers that allow hosting constrained windows should
+// implement this protocol.
+@protocol ConstrainedWindowSupport
+
+// Requests that |window| is opened as a per-tab sheet to the current tab.
+- (void)attachConstrainedWindow:(ConstrainedWindowMac*)window;
+
+// Closes the tab sheet |window| and potentially shows the next sheet in the
+// tab's sheet queue.
+- (void)removeConstrainedWindow:(ConstrainedWindowMac*)window;
+
+// Returns NO if constrained windows cannot be attached to this window.
+- (BOOL)canAttachConstrainedWindow;
+
+@end
+
 // Base class for constrained dialog delegates. Never inherit from this
 // directly.
 class ConstrainedWindowMacDelegate {
@@ -124,7 +140,7 @@ class ConstrainedWindowMac : public ConstrainedWindow {
   ConstrainedWindowMacDelegate* delegate() { return delegate_; }
 
   // Makes the constrained window visible, if it is not yet visible.
-  void Realize(BrowserWindowController* controller);
+  void Realize(NSWindowController<ConstrainedWindowSupport>* controller);
 
  private:
   friend class ConstrainedWindow;
@@ -136,7 +152,7 @@ class ConstrainedWindowMac : public ConstrainedWindow {
   ConstrainedWindowMacDelegate* delegate_;
 
   // Controller of the window that contains this sheet.
-  BrowserWindowController* controller_;
+  NSWindowController<ConstrainedWindowSupport>* controller_;
 
   // Stores if |ShowConstrainedWindow()| was called.
   bool should_be_visible_;