[MacViews] Position modal sheets using ModalDialogHost.

chrome/browser/ui/views/apps/app_window_native_widget_mac.mm

Index: chrome/browser/ui/views/apps/app_window_native_widget_mac.mm
diff --git a/chrome/browser/ui/views/apps/app_window_native_widget_mac.mm b/chrome/browser/ui/views/apps/app_window_native_widget_mac.mm
index 1bab9b8373373bc19105d504b911f2a1fee03e52..8c06a87326391e6dcb00744b7b5be6a6cdfdb9b9 100644
--- a/chrome/browser/ui/views/apps/app_window_native_widget_mac.mm
+++ b/chrome/browser/ui/views/apps/app_window_native_widget_mac.mm
@@ -20,6 +20,11 @@ AppWindowNativeWidgetMac::AppWindowNativeWidgetMac(
 AppWindowNativeWidgetMac::~AppWindowNativeWidgetMac() {
 }
 
+int AppWindowNativeWidgetMac::SheetPositionY() {
+  NSWindow* ns_window = GetNativeWindow();
+  return NSHeight([ns_window frame]) - NSMaxY([[ns_window contentView] frame]);

[tapted, 2015/08/26 03:20:41]

how does this look for frameless widgets? (is it consistent with Cocoa?)

[jackhou1, 2015/08/26 07:02:08]

I had tried this with the USB selector dialog, but it turns out that's actually
WebContents modal. I'm not sure if there are any window-modal dialogs on app
windows. There's only one override of -willPositionSheet in the codebase, and
it's on BrowserWindowControllerPrivate, so presumably any modal sheets on app
windows will do the default, which is to show it at the top of the contentView
frame.

+}
+
 NSWindow* AppWindowNativeWidgetMac::CreateNSWindow(
     const views::Widget::InitParams& params) {
   // If the window has a native or colored frame, use the same NSWindow as