fix(theme-picker) fix theme picker bugs on mobile

Closes angular#495

Author: philip-firstorder

src/app/shared/theme-picker/theme-picker.ts

@@ -63,7 +63,10 @@ export class ThemePicker {
     if (theme.isDefault) {
       this.styleManager.removeStyle('theme');
     } else {
-      this.styleManager.setStyle('theme', `assets/${theme.href}`);
+      // use timout to fix https://github.com/angular/material.angular.io/issues/495
+      setTimeout(() => {
+        this.styleManager.setStyle('theme', `assets/${theme.href}`);
+      });
     }
 
     if (this.currentTheme) {