WebUI: Fix type errors in cr_elements, when stricter flags are used.

These errors only show up if tools/typescript/tsconfig_base_lit.json
is used as the configuration, which unfortunately is not yet possible,
due to still maintaining several Polymer files (mostly Mixins) under
the same ts_library() target.

Bug: 40943652
Change-Id: I648af0148f0e4daafe3103077dc5d66be5263a09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5540235
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1301631}

ui/webui/resources/cr_elements/cr_button/cr_button.ts

@@ -59,8 +59,8 @@ export class CrButtonElement extends CrButtonElementBase {
   }
 
   disabled: boolean = false;
-  private hasPrefixIcon_: boolean = false;
-  private hasSuffixIcon_: boolean = false;
+  protected hasPrefixIcon_: boolean = false;
+  protected hasSuffixIcon_: boolean = false;
 
   /**
    * It is possible to activate a tab when the space key is pressed down. When

ui/webui/resources/cr_elements/cr_dialog/cr_dialog.ts

@@ -111,7 +111,6 @@ export class CrDialogElement extends CrDialogElementBase {
   showOnAttach: boolean = false;
   ariaDescriptionText?: string;
 
-  private intersectionObserver_: IntersectionObserver|null = null;
   private mutationObserver_: MutationObserver|null = null;
   private boundKeydown_: ((e: KeyboardEvent) => void)|null = null;
 

ui/webui/resources/cr_elements/cr_drawer/cr_drawer.ts

@@ -49,7 +49,7 @@ export class CrDrawerElement extends CrLitElement {
 
   heading: string;
   align: 'ltr'|'rtl' = 'ltr';
-  private show_: boolean;
+  protected show_: boolean = false;
 
   get open(): boolean {
     return this.$.dialog.open;

ui/webui/resources/cr_elements/cr_icon/cr_icon.ts

@@ -40,8 +40,8 @@ export class CrIconElement extends CrLitElement {
 
     if (changedProperties.has('icon')) {
       const [iconsetName, iconName] = this.icon.split(':');
-      this.iconName_ = iconName;
-      this.iconsetName_ = iconsetName;
+      this.iconName_ = iconName || '';
+      this.iconsetName_ = iconsetName || '';
       this.updateIcon();
     }
   }

ui/webui/resources/cr_elements/cr_icon_button/cr_icon_button.ts

@@ -99,7 +99,7 @@ export class CrIconButtonElement extends CrIconbuttonElementBase {
 
   disabled: boolean = false;
   ironIcon?: string;
-  private multipleIcons_: boolean = false;
+  protected multipleIcons_: boolean = false;
 
   /**
    * It is possible to activate a tab when the space key is pressed down. When

ui/webui/resources/cr_elements/cr_selectable_mixin.ts

@@ -87,7 +87,6 @@ export const CrSelectableMixin = <T extends Constructor<CrLitElement>>(
     selectOnClick: boolean = true;
 
     private items_: Element[] = [];
-    private observer_: MutationObserver;
     private selectedItem_: Element|null = null;
 
     override firstUpdated(changedProperties: PropertyValues<this>) {

ui/webui/resources/cr_elements/cr_slider/cr_slider.ts

@@ -180,10 +180,10 @@ export class CrSliderElement extends CrSliderElementBase {
   ticks: SliderTick[]|number[] = [];
   value: number;
 
-  private disabled_: boolean;
+  protected disabled_: boolean;
   protected label_: string = '';
-  private showLabel_: boolean = false;
-  private transiting_: boolean = false;
+  protected showLabel_: boolean = false;
+  protected transiting_: boolean = false;
 
   private deltaKeyMap_: Map<string, number>|null = null;
   private draggingEventTracker_: EventTracker|null = null;

ui/webui/resources/cr_elements/cr_tabs/cr_tabs.ts

@@ -65,7 +65,6 @@ export class CrTabsElement extends CrLitElement {
   selected: number;
 
   private isRtl_: boolean = false;
-  private lastSelected_: number|null = null;
 
   override connectedCallback() {
     super.connectedCallback();

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar.ts

@@ -96,14 +96,14 @@ export class CrToolbarElement extends CrLitElement {
   searchPrompt: string;
   clearLabel: string;
   menuLabel: string;
-  spinnerActive: boolean;
+  spinnerActive: boolean = false;
   showMenu: boolean = false;
   showSearch: boolean = true;
   override autofocus: boolean = false;
-  narrow: boolean;
+  narrow: boolean = false;
   narrowThreshold: number = 900;
   alwaysShowLogo: boolean = false;
-  protected showingSearch_: boolean;
+  protected showingSearch_: boolean = false;
   searchIconOverride?: string;
   private narrowQuery_: MediaQueryList|null = null;
 

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.ts

@@ -76,11 +76,11 @@ export class CrToolbarSearchFieldElement extends
     };
   }
 
-  narrow: boolean;
+  narrow: boolean = false;
   showingSearch: boolean = false;
   disabled: boolean = false;
   override autofocus: boolean = false;
-  spinnerActive: boolean;
+  spinnerActive: boolean = false;
   private searchFocused_: boolean = false;
   iconOverride?: string;
 

ui/webui/resources/cr_elements/cr_url_list_item/cr_url_list_item.ts

@@ -120,7 +120,7 @@ export class CrUrlListItemElement extends CrUrlListItemElementBase {
     };
   }
 
-  alwaysShowSuffix: boolean;
+  alwaysShowSuffix: boolean = false;
   asAnchor: boolean = false;
   itemAriaLabel?: string;
   itemAriaDescription?: string;
@@ -128,9 +128,9 @@ export class CrUrlListItemElement extends CrUrlListItemElementBase {
   description?: string;
   reverseElideDescription: boolean = false;
   hasBadges: boolean = false;
-  private hasDescriptions_: boolean = false;
-  private hasSlottedContent_: boolean = false;
-  private isFolder_: boolean = false;
+  protected hasDescriptions_: boolean = false;
+  protected hasSlottedContent_: boolean = false;
+  protected isFolder_: boolean = false;
   size: CrUrlListItemSize = CrUrlListItemSize.MEDIUM;
   override title: string = '';
   url?: string;