fix(docs-infra): Handle search criteria from Chrome search providers (#30345)

fixes #30242

PR Close #30345

aio/src/app/search/search-box/search-box.component.spec.ts

@@ -44,6 +44,16 @@ describe('SearchBoxComponent', () => {
       expect(host.searchHandler).toHaveBeenCalledWith('initial search');
       expect(component.searchBox.nativeElement.value).toEqual('initial search');
     })));
+
+    it('should decode the search query from the location service (chrome search provider format)',
+          fakeAsync(inject([LocationService], (location: MockLocationService) => {
+      location.search.and.returnValue({ search: 'initial+search' });
+      component.ngAfterViewInit();
+      expect(location.search).toHaveBeenCalled();
+      tick(300);
+      expect(host.searchHandler).toHaveBeenCalledWith('initial search');
+      expect(component.searchBox.nativeElement.value).toEqual('initial search');
+    })));
   });
 
   describe('onSearch', () => {

aio/src/app/search/search-box/search-box.component.ts

@@ -43,7 +43,7 @@ export class SearchBoxComponent implements AfterViewInit {
   ngAfterViewInit() {
     const query = this.locationService.search()['search'];
     if (query) {
-      this.query = query;
+      this.query = this.decodeQuery(query);
       this.doSearch();
     }
   }
@@ -60,6 +60,11 @@ export class SearchBoxComponent implements AfterViewInit {
     this.searchBox.nativeElement.focus();
   }
 
+  private decodeQuery(query: string): string {
+    // `decodeURIComponent` does not handle `+` for spaces, replace via RexEx.
+    return query.replace(/\+/g, ' ');
+  }
+
   private get query() { return this.searchBox.nativeElement.value; }
   private set query(value: string) { this.searchBox.nativeElement.value = value; }
 }