From bc207ff2da2ad9a415979a61695f2a0edb453b19 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Fern=C3=A1ndez=20Haro?=
 <alejandro.haro@elastic.co>
Date: Wed, 17 Feb 2021 10:01:55 +0000
Subject: [PATCH] [Application Usage] Remove deprecated & unused
 legacy.appChanged API (#91464)

---
 src/plugins/usage_collection/public/mocks.tsx |  3 ---
 .../usage_collection/public/plugin.tsx        | 25 +++++--------------
 2 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/src/plugins/usage_collection/public/mocks.tsx b/src/plugins/usage_collection/public/mocks.tsx
index ff8740ea48f7b..72cefaf026490 100644
--- a/src/plugins/usage_collection/public/mocks.tsx
+++ b/src/plugins/usage_collection/public/mocks.tsx
@@ -36,9 +36,6 @@ const createSetupContract = (): Setup => {
     allowTrackUserAgent: jest.fn(),
     reportUiCounter: jest.fn(),
     METRIC_TYPE,
-    __LEGACY: {
-      appChanged: jest.fn(),
-    },
   };
 
   return setupContract;
diff --git a/src/plugins/usage_collection/public/plugin.tsx b/src/plugins/usage_collection/public/plugin.tsx
index ac566c6a0d044..6d1eb751d907a 100644
--- a/src/plugins/usage_collection/public/plugin.tsx
+++ b/src/plugins/usage_collection/public/plugin.tsx
@@ -7,17 +7,17 @@
  */
 
 import { Reporter, METRIC_TYPE, ApplicationUsageTracker } from '@kbn/analytics';
-import { Subject, merge, Subscription } from 'rxjs';
+import type { Subscription } from 'rxjs';
 import React from 'react';
-import { Storage } from '../../kibana_utils/public';
-import { createReporter, trackApplicationUsageChange } from './services';
-import {
+import type {
   PluginInitializerContext,
   Plugin,
   CoreSetup,
   CoreStart,
   HttpSetup,
-} from '../../../core/public';
+} from 'src/core/public';
+import { Storage } from '../../kibana_utils/public';
+import { createReporter, trackApplicationUsageChange } from './services';
 import { ApplicationUsageContext } from './components/track_application_view';
 
 export interface PublicConfigType {
@@ -39,15 +39,6 @@ export interface UsageCollectionSetup {
   applicationUsageTracker: IApplicationUsageTracker;
   reportUiCounter: Reporter['reportUiCounter'];
   METRIC_TYPE: typeof METRIC_TYPE;
-  __LEGACY: {
-    /**
-     * Legacy handler so we can report the actual app being used inside "kibana#/{appId}".
-     * To be removed when we get rid of the legacy world
-     *
-     * @deprecated
-     */
-    appChanged: (appId: string) => void;
-  };
 }
 
 export interface UsageCollectionStart {
@@ -65,7 +56,6 @@ export function isUnauthenticated(http: HttpSetup) {
 }
 
 export class UsageCollectionPlugin implements Plugin<UsageCollectionSetup, UsageCollectionStart> {
-  private readonly legacyAppId$ = new Subject<string>();
   private applicationUsageTracker?: ApplicationUsageTracker;
   private trackUserAgent: boolean = true;
   private subscriptions: Subscription[] = [];
@@ -103,9 +93,6 @@ export class UsageCollectionPlugin implements Plugin<UsageCollectionSetup, Usage
       },
       reportUiCounter: this.reporter.reportUiCounter,
       METRIC_TYPE,
-      __LEGACY: {
-        appChanged: (appId) => this.legacyAppId$.next(appId),
-      },
     };
   }
 
@@ -118,7 +105,7 @@ export class UsageCollectionPlugin implements Plugin<UsageCollectionSetup, Usage
       this.reporter.start();
       this.applicationUsageTracker.start();
       this.subscriptions = trackApplicationUsageChange(
-        merge(application.currentAppId$, this.legacyAppId$),
+        application.currentAppId$,
         this.applicationUsageTracker
       );
     }