[cr133] VectorIcon default constructor made private

This change corrects all places where a default vector was being used to
now use `VectorIcon::EmptyIcon()`, which is the correct way to retrieve
a default empty vector icon.

Chromium change:
https://chromium.googlesource.com/chromium/src/+/76462a6abb5b146cca49f95c8559d548304ad77b

commit 76462a6abb5b146cca49f95c8559d548304ad77b
Author: Peter Kasting <[email protected]>
Date:   Thu Jan 2 13:00:15 2025 -0800

    Prevent default construction of VectorIcon.

    This avoids obscure bugs when VectorIcons are stored or compared based
    on address and the default (empty) icon is involved. Instead add a
    getter that returns a ref to a singleton empty icon.

    This obviates the need for kNoneIcon, which can't be made to work with
    these changes (easily, anyway), so that's replaced also.

    Bug: 364987728

Author: cdesouza-chromium

chromium_src/chrome/browser/ui/content_settings/content_setting_image_model.cc

@@ -7,6 +7,7 @@
 
 #include "brave/browser/ui/content_settings/brave_content_setting_image_models.h"
 #include "brave/components/vector_icons/vector_icons.h"
+#include "ui/gfx/vector_icon_types.h"
 
 #define GenerateContentSettingImageModels \
   GenerateContentSettingImageModels_ChromiumImpl
@@ -27,7 +28,8 @@ void ContentSettingImageModel::GetIconFromType(
     raw_ptr<const gfx::VectorIcon>* icon,
     raw_ptr<const gfx::VectorIcon>* badge) {
   if (type == ContentSettingsType::AUTOPLAY) {
-    *badge = (blocked ? &vector_icons::kBlockedBadgeIcon : &gfx::kNoneIcon);
+    *badge = (blocked ? &vector_icons::kBlockedBadgeIcon
+                      : &gfx::VectorIcon::EmptyIcon());
     *icon = &kAutoplayStatusIcon;
   } else {
     ::GetIconFromType(type, blocked, icon, badge);

chromium_src/chrome/browser/ui/views/profiles/profile_menu_view.cc

@@ -6,10 +6,6 @@
 #include "chrome/app/vector_icons/vector_icons.h"
 #include "ui/gfx/vector_icon_types.h"
 
-namespace {
-constexpr gfx::VectorIcon kGuestMenuEmptyArtIcon;
-}  // namespace
-
-#define kGuestMenuArtIcon kGuestMenuEmptyArtIcon
+#define kGuestMenuArtIcon gfx::VectorIcon::EmptyIcon()
 #include "src/chrome/browser/ui/views/profiles/profile_menu_view.cc"
 #undef kGuestMenuArtIcon