Return preferred size of the system web dialog when laptop's lid is closed

SystemWebDialogDelegate::ComputeDialogSizeForInternalScreen() returns a
valid dialog size only if the internal screen is available or if there
is no internal screen in the device hardware. There is another edge case
where the laptop's lid is closed which makes the internal screen
unavailable. We were previously not handling this edge case and returned
a (0,0) size for these dialogs. The fix is to return the preferred size
for this edge case.

Fixed: 1157591
Change-Id: I023dfcde33a1099aa14ac487e9ad109c1b9ad3a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2590688
Commit-Queue: Jimmy Gong <jimmyxgong@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836918}

chrome/browser/ui/webui/chromeos/system_web_dialog_delegate.cc

@@ -70,17 +70,21 @@ gfx::Size SystemWebDialogDelegate::ComputeDialogSizeForInternalScreen(
   if (!display::Display::HasInternalDisplay())
     return preferred_size;
 
-  // According to the Chrome OS dialog spec, dialogs should have a 48px margin
-  // from the edge of an internal display.
-  static const gfx::Insets margins =
-      gfx::Insets(kDialogMarginForInternalScreenPx);
-
   display::Display internal_display;
   if (!display::Screen::GetScreen()->GetDisplayWithDisplayId(
           display::Display::InternalDisplayId(), &internal_display)) {
-    NOTREACHED() << "Could not fetch metadata for internal display.";
+    // GetDisplayWithDisplayId() returns false if the laptop's lid is closed.
+    // Return the preferred size instead.
+    // TODO(crbug/1158631): Test this edge case with displays
+    // (lid closed with external monitors).
+    return preferred_size;
   }
 
+  // According to the Chrome OS dialog spec, dialogs should have a 48px margin
+  // from the edge of an internal display.
+  static const gfx::Insets margins =
+      gfx::Insets(kDialogMarginForInternalScreenPx);
+
   // Work area size does not include the status bar.
   gfx::Size work_area_size = internal_display.work_area_size();