[MacViews] Position modal sheets using ModalDialogHost.

chrome/browser/ui/views/frame/browser_frame_mac.mm

Index: chrome/browser/ui/views/frame/browser_frame_mac.mm
diff --git a/chrome/browser/ui/views/frame/browser_frame_mac.mm b/chrome/browser/ui/views/frame/browser_frame_mac.mm
index 2d9aa266b431e81973ffbcc22024616e104a8b70..7b8f6c1e3d0c531978d145d8cc426718261a308e 100644
--- a/chrome/browser/ui/views/frame/browser_frame_mac.mm
+++ b/chrome/browser/ui/views/frame/browser_frame_mac.mm
@@ -8,6 +8,7 @@
 #include "chrome/browser/ui/views/frame/browser_shutdown.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #import "chrome/browser/ui/views/frame/native_widget_mac_frameless_nswindow.h"
+#include "components/web_modal/web_contents_modal_dialog_host.h"
 #import "ui/base/cocoa/window_size_constants.h"
 
 BrowserFrameMac::BrowserFrameMac(BrowserFrame* browser_frame,
@@ -29,6 +30,15 @@ void BrowserFrameMac::OnWindowWillClose() {
   NativeWidgetMac::OnWindowWillClose();
 }
 
+int BrowserFrameMac::SheetPositionY() {
+  web_modal::WebContentsModalDialogHost* dialog_host =
+      browser_view_->GetWebContentsModalDialogHost();
+  NSView* host_view = dialog_host->GetHostView();

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

I think I need a comment about the logic here.

E.g. mention why not simply GetDialogPosition(..).y() and a summary

Also does this work equivalently well in mac_views_browser?

And, do you think it's worth separating GetDialogPosition() into
GetChildModalDialogPosition() and GetWindowModalDialogPosition()?

[jackhou1, 2015/08/26 07:02:09]

Done.
This only applies to mac_views_browser since positioning is done by the parent
window.
 
Nup, I think this is the only caller that wants the position relative to the
window.

+  int host_view_y =
+      NSHeight([[host_view window] frame]) - NSMaxY([host_view frame]);
+  return host_view_y + dialog_host->GetDialogPosition(gfx::Size()).y();
+}
+
 void BrowserFrameMac::InitNativeWidget(
     const views::Widget::InitParams& params) {
   views::NativeWidgetMac::InitNativeWidget(params);