Clamp dialog bounds to be fully visible on the nearest display

components/constrained_window/constrained_window_views.cc

Index: components/constrained_window/constrained_window_views.cc
diff --git a/components/constrained_window/constrained_window_views.cc b/components/constrained_window/constrained_window_views.cc
index 3ed86ce06852a9da707d5868000e19a7103a8b7d..762f6ae83819fed0229649914f28192593a99bac 100644
--- a/components/constrained_window/constrained_window_views.cc
+++ b/components/constrained_window/constrained_window_views.cc
@@ -13,6 +13,9 @@
 #include "components/web_modal/web_contents_modal_dialog_host.h"
 #include "components/web_modal/web_contents_modal_dialog_manager.h"
 #include "components/web_modal/web_contents_modal_dialog_manager_delegate.h"
+#include "ui/display/display.h"
+#include "ui/display/display_finder.h"
+#include "ui/display/screen.h"
 #include "ui/views/border.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_observer.h"
@@ -80,6 +83,18 @@ class WidgetModalDialogHostObserverViews
   DISALLOW_COPY_AND_ASSIGN(WidgetModalDialogHostObserverViews);
 };
 
+gfx::Point MoveRectToNearestHostDisplay(const gfx::Rect& screen_rect,

[msw, 2016/12/14 22:37:08]

Inline this function or rename it, since it doesn't actually move (mutate) a
rect (eg. GetOriginForRectToFitOnDisplay or similar).

+                                        const gfx::Rect& host_rect) {
+  gfx::Rect display_rect = screen_rect;
+  const display::Display* display = display::FindDisplayNearestPoint(

[msw, 2016/12/14 22:37:08]

Use Screen::GetDisplayNearestWindow(dialog_host->GetHostView()).

+      display::Screen::GetScreen()->GetAllDisplays(), host_rect.CenterPoint());
+  DCHECK(display);

[msw, 2016/12/14 22:37:08]

optional nit: DCHECK immediately before deference isn't necessary.

+  const gfx::Rect work_area = display->work_area();
+  if (!work_area.Contains(display_rect))
+    display_rect.AdjustToFit(work_area);
+  return display_rect.origin();
+}
+
 void UpdateModalDialogPosition(views::Widget* widget,
                                web_modal::ModalDialogHost* dialog_host,
                                const gfx::Size& size) {
@@ -108,8 +123,14 @@ void UpdateModalDialogPosition(views::Widget* widget,
     position.set_y(position.y() - border->GetInsets().top());
   }
 
-  if (widget->is_top_level())
+  if (widget->is_top_level()) {
     position += host_widget->GetClientAreaBoundsInScreen().OffsetFromOrigin();
+    // If the dialog extends partially off any display, clamp its position to

[msw, 2016/12/14 22:37:08]

This should be a function comment on the helper (unless you inline it).

+    // be fully visible within that display. If the dialog doesn't intersect
+    // with any display clamp its position to be fully on the nearest display.
+    position = MoveRectToNearestHostDisplay(
+        gfx::Rect(position, size), host_widget->GetWindowBoundsInScreen());
+  }
 
   widget->SetBounds(gfx::Rect(position, size));
 }