MacViews: Exploring removal of window-modal sheets.

chrome/browser/ui/cocoa/web_contents_modal_dialog_host_cocoa.mm

 // Copyright 2015 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.
 
 #include "chrome/browser/ui/cocoa/web_contents_modal_dialog_host_cocoa.h"
 
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/tab_dialogs.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet_controller.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/size.h"
+#import "ui/gfx/mac/coordinate_conversion.h"
 
 WebContentsModalDialogHostCocoa::WebContentsModalDialogHostCocoa(
     ConstrainedWindowSheetController* sheet_controller)
     : sheet_controller_(sheet_controller) {
 }
 
 WebContentsModalDialogHostCocoa::~WebContentsModalDialogHostCocoa() {
-  // Toolkit-Views calls OnHostDestroying on observers here, but the Cocoa host
-  // doesn't need to be observed.
+  for (auto& observer : observers_)
+    observer.OnHostDestroying();
+}
+
+void WebContentsModalDialogHostCocoa::OnPositionRequiresUpdate() {
+  for (auto& observer : observers_)
+    observer.OnPositionRequiresUpdate();
 }
 
 gfx::NativeView WebContentsModalDialogHostCocoa::GetHostView() const {
   // To avoid the constrained window controller having to know about the browser
   // view layout, use the active tab in the parent window.
   NSWindow* parent_window = [sheet_controller_ parentWindow];
   Browser* browser = chrome::FindBrowserWithWindow(parent_window);
   // This could be null for packaged app windows, but this dialog host is
   // currently only used for browsers.
   DCHECK(browser);
   content::WebContents* web_contents =
       browser->tab_strip_model()->GetActiveWebContents();
   DCHECK(web_contents);
   TabDialogs* tab_dialogs = TabDialogs::FromWebContents(web_contents);
   DCHECK(tab_dialogs);
 
   // Note this returns the WebContents' superview, so it doesn't really matter
   // which WebContents inside the browser we actually chose above.
   return tab_dialogs->GetDialogParentView();
 }
 
 gfx::Point WebContentsModalDialogHostCocoa::GetDialogPosition(
     const gfx::Size& size) {
-  // Dialogs are always re-positioned by the constrained window sheet controller
-  // so nothing interesting to return yet.
-  return gfx::Point();
+  // Web-modals go via [sheet_controller_ originForSheet:..]. This is invoked
+  // for window-modals, so use the NSWindow sheet APIs.
+  NSWindow* native_parent = [sheet_controller_ parentWindow];
+  NSRect proposed_rect = [[native_parent contentView] bounds];
+  proposed_rect.origin.y = proposed_rect.size.height;
+  proposed_rect.size.height = 0;
+
+  id parent_delegate = [native_parent delegate];
+  if ([parent_delegate
+          respondsToSelector:@selector(window:willPositionSheet:usingRect:)]) {
+    proposed_rect = [parent_delegate window:native_parent
+                          willPositionSheet:nil
+                                  usingRect:proposed_rect];
+  }
+
+  // Center horizontally and flip vertically. Note that origin.x may go
+  // negative. (That means it can also go offscreen.)
+  return gfx::Point(NSMidX(proposed_rect) - size.width() / 2,
+                    NSHeight([native_parent frame]) - proposed_rect.origin.y);
+}
+
+gfx::Point WebContentsModalDialogHostCocoa::GetHostPosition() const {
+  return gfx::ScreenRectFromNSRect([[sheet_controller_ parentWindow] frame])
+      .origin();
 }
 
 void WebContentsModalDialogHostCocoa::AddObserver(
     web_modal::ModalDialogHostObserver* observer) {
-  NOTREACHED();
+  observers_.AddObserver(observer);
 }
 void WebContentsModalDialogHostCocoa::RemoveObserver(
     web_modal::ModalDialogHostObserver* observer) {
-  NOTREACHED();
+  observers_.RemoveObserver(observer);
 }
 
 gfx::Size WebContentsModalDialogHostCocoa::GetMaximumDialogSize() {
   // The dialog should try to fit within the overlay for the web contents.
   // Note that, for things like print preview, this is just a suggested maximum.
   return gfx::Size(
       [sheet_controller_ overlayWindowSizeForParentView:GetHostView()]);
 }