CCA: Check external monitor with screen backlight off

Add check of no external monitor plugged in with screen backlight forced
off event to judge whether to suspend camera stream.

Bug: 1114967
Test: Pluggin both external camera and external monitor, check CCA's
preview is still on after closing lid of device.

Change-Id: Ia07e1efe9d21814521a62a4ad1c63324221b991d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351579Reviewed-by: Shik Chen <shik@chromium.org>
Commit-Queue: Kuo Jen Wei <inker@chromium.org>
Auto-Submit: Kuo Jen Wei <inker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797514}

chromeos/components/camera_app_ui/resources/src/js/state.js

@@ -24,6 +24,7 @@ export const State = {
   GRID_GOLDEN: 'golden',
   GRID: 'grid',
   HAS_BACK_CAMERA: 'has-back-camera',
+  HAS_EXTERNAL_SCREEN: 'has-external-screen',
   HAS_FRONT_CAMERA: 'has-front-camera',
   MAX_WND: 'max-wnd',
   MIC: 'mic',

chromeos/components/camera_app_ui/resources/src/js/views/camera.js

@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 import {browserProxy} from '../browser_proxy/browser_proxy.js';
-import {assert, assertInstanceof} from '../chrome_util.js';
+import {assert, assertInstanceof, promisify} from '../chrome_util.js';
 import {
   PhotoConstraintsPreferrer,  // eslint-disable-line no-unused-vars
   VideoConstraintsPreferrer,  // eslint-disable-line no-unused-vars
@@ -257,10 +257,6 @@ export class Camera extends View {
         this.start();
       }
     });
-
-    state.addObserver(state.State.SCREEN_OFF_AUTO, () => this.start());
-
-    this.configuring_ = null;
   }
 
   /**
@@ -280,6 +276,34 @@ export class Camera extends View {
     };
     const screenState = await helper.initScreenStateMonitor(setScreenOffAuto);
     setScreenOffAuto(screenState);
+
+    const updateExternalScreen = async () => {
+      const allInfo = await promisify(chrome.system.display.getInfo)(
+          {singleUnified: false});
+      const hasExternalScreen = allInfo.some(({isInternal}) => !isInternal);
+      state.set(state.State.HAS_EXTERNAL_SCREEN, hasExternalScreen);
+    };
+    await updateExternalScreen();
+    chrome.system.display.onDisplayChanged.addListener(updateExternalScreen);
+
+    const checkScreenOff = () => {
+      if (this.screenOff_) {
+        this.start();
+      }
+    };
+
+    state.addObserver(state.State.SCREEN_OFF_AUTO, checkScreenOff);
+    state.addObserver(state.State.HAS_EXTERNAL_SCREEN, checkScreenOff);
+  }
+
+  /**
+   * @return {boolean} If the App window is invisible to user with respect to
+   * screen off state.
+   * @private
+   */
+  get screenOff_() {
+    return state.get(state.State.SCREEN_OFF_AUTO) &&
+        !state.get(state.State.HAS_EXTERNAL_SCREEN);
   }
 
   /**
@@ -305,8 +329,8 @@ export class Camera extends View {
    */
   isSuspended() {
     return this.locked_ || browserProxy.isMinimized() ||
-        state.get(state.State.SUSPEND) ||
-        state.get(state.State.SCREEN_OFF_AUTO) || this.isTabletBackground_();
+        state.get(state.State.SUSPEND) || this.screenOff_ ||
+        this.isTabletBackground_();
   }
 
   /**

chromeos/components/camera_app_ui/resources/src/manifest.json

@@ -15,6 +15,7 @@
     "videoCapture",
     "audioCapture",
     "storage",
+    "system.display",
     "unlimitedStorage",
     "chromeosInfoPrivate",
     "metricsPrivate",