CCA: Migrate type.js and util.js to TypeScript

Bug: b:172340451
Test: tast run <ip> camera.CCAUISmoke* camera.CCAUIStress*
Change-Id: I181672dc9be6db1123ab220dcc41cd8ec631847b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3291015
Reviewed-by: Shik Chen <shik@chromium.org>
Commit-Queue: Pi-Hsun Shih <pihsun@chromium.org>
Cr-Commit-Position: refs/heads/main@{#949997}

ash/webui/camera_app_ui/resources/js/js.gni

@@ -63,13 +63,13 @@ compile_js_files = [
   "timer.js",
   "toast.js",
   "tooltip.js",
-  "type.js",
+  "type.ts",
   "unload.js",
   "untrusted_ga_helper.js",
   "untrusted_helper_interfaces.js",
   "untrusted_script_loader.js",
   "untrusted_video_processor_helper.js",
-  "util.js",
+  "util.ts",
   "views/camera_intent.js",
   "views/camera.js",
   "views/camera/layout.js",

ash/webui/camera_app_ui/resources/js/main.js

@@ -40,6 +40,7 @@ import {
 } from './type.js';
 import {addUnloadCallback} from './unload.js';
 import * as util from './util.js';
+import {checkEnumVariant} from './util.js';
 import {Camera} from './views/camera.js';
 import {CameraIntent} from './views/camera_intent.js';
 import {Dialog} from './views/dialog.js';
@@ -396,27 +397,9 @@ function parseSearchParams() {
   const url = new URL(window.location.href);
   const params = url.searchParams;
 
-  // TODO(pihsun): Intent.create has almost same code for checking a string is
-  // an enum variant, extract them to a util function when we change TypeScript
-  // since the util function type is hard to be described in closure compiler
-  // due to lack of generic type bounds.
-  /** @type {?Facing} */
-  const facing = (() => {
-    const facing = params.get('facing');
-    if (facing === null || !Object.values(Facing).includes(facing)) {
-      return null;
-    }
-    return /** @type {!Facing} */ (facing);
-  })();
+  const facing = checkEnumVariant(Facing, params.get('facing'));
 
-  /** @type {?Mode} */
-  const mode = (() => {
-    const mode = params.get('mode');
-    if (mode === null || !Object.values(Mode).includes(mode)) {
-      return null;
-    }
-    return /** @type {!Mode} */ (mode);
-  })();
+  const mode = checkEnumVariant(Mode, params.get('mode'));
 
   /** @type {?Intent} */
   const intent = (() => {
@@ -486,28 +469,33 @@ let instance = null;
       appWindow.reportPerf({event, duration, perfInfo});
     }
   });
-  const states = Object.values(PerfEvent);
-  states.push(state.State.TAKING);
-  states.forEach((s) => {
-    state.addObserver(s, (val, extras) => {
-      let event = s;
-      if (s === state.State.TAKING) {
-        // 'taking' state indicates either taking photo or video. Skips for
-        // video-taking case since we only want to collect the metrics of
-        // photo-taking.
-        if (state.get(Mode.VIDEO)) {
-          return;
-        }
-        event = PerfEvent.PHOTO_TAKING;
-      }
 
+  state.addObserver(state.State.TAKING, (val, extras) => {
+    // 'taking' state indicates either taking photo or video. Skips for
+    // video-taking case since we only want to collect the metrics of
+    // photo-taking.
+    if (state.get(Mode.VIDEO)) {
+      return;
+    }
+    const event = PerfEvent.PHOTO_TAKING;
+
+    if (val) {
+      perfLogger.start(event);
+    } else {
+      perfLogger.stop(event, extras);
+    }
+  });
+
+  const states = Object.values(PerfEvent);
+  for (const event of states) {
+    state.addObserver(event, (val, extras) => {
       if (val) {
         perfLogger.start(event);
       } else {
         perfLogger.stop(event, extras);
       }
     });
-  });
+  }
 
   instance = new App({perfLogger, intent, facing, mode});
   await instance.start(

ash/webui/camera_app_ui/resources/js/mojo/device_operator.js

@@ -681,10 +681,7 @@ export class DeviceOperator {
   /**
    * Creates a new instance of DeviceOperator if it is not set. Returns the
    *     exist instance.
-   * TODO(b/172340451): Use force casting rather than template for the type
-   *     checking of Proxy after switching to TypeScript.
-   * @return {!Promise<?T>} The singleton instance.
-   * @template T
+   * @return {!Promise<!DeviceOperator>} The singleton instance.
    */
   static async getInstance() {
     await readyEvent.wait();
@@ -705,7 +702,7 @@ export class DeviceOperator {
         return target[property];
       },
     };
-    return /** @type {!T} */ (new Proxy(instance, deviceOperatorWrapper));
+    return new Proxy(instance, deviceOperatorWrapper);
   }
 
   /**