Render Watcher title in tab and clear it on unmount.

- Refactor boot file to follow index-oriented pattern of other plugins.

Author: cjcenizal

x-pack/plugins/watcher/public/application/boot.tsx renamed to x-pack/plugins/watcher/public/application/index.tsx

@@ -17,7 +17,7 @@ interface BootDeps extends AppDeps {
   I18nContext: any;
 }
 
-export const boot = (bootDeps: BootDeps) => {
+export const renderApp = (bootDeps: BootDeps) => {
   const { I18nContext, element, savedObjects, ...appDeps } = bootDeps;
 
   setHttpClient(appDeps.http);
@@ -29,6 +29,7 @@ export const boot = (bootDeps: BootDeps) => {
     </I18nContext>,
     element
   );
+
   return () => {
     unmountComponentAtNode(element);
   };

x-pack/plugins/watcher/public/plugin.ts

@@ -30,20 +30,31 @@ export class WatcherUIPlugin implements Plugin<void, void, Dependencies, any> {
   ) {
     const esSection = management.sections.section.insightsAndAlerting;
 
+    const pluginName = i18n.translate(
+      'xpack.watcher.sections.watchList.managementSection.watcherDisplayName',
+      { defaultMessage: 'Watcher' }
+    );
+
     const watcherESApp = esSection.registerApp({
       id: 'watcher',
-      title: i18n.translate(
-        'xpack.watcher.sections.watchList.managementSection.watcherDisplayName',
-        { defaultMessage: 'Watcher' }
-      ),
+      title: pluginName,
       order: 3,
       mount: async ({ element, setBreadcrumbs, history }) => {
-        const [core] = await getStartServices();
-        const { i18n: i18nDep, docLinks, savedObjects, application } = core;
-        const { boot } = await import('./application/boot');
+        const [coreStart] = await getStartServices();
+        const {
+          chrome: { docTitle },
+          i18n: i18nDep,
+          docLinks,
+          savedObjects,
+          application,
+        } = coreStart;
+
+        docTitle.change(pluginName);
+
+        const { renderApp } = await import('./application');
         const { TimeBuckets } = await import('./legacy');
 
-        return boot({
+        const unmountAppCallback = renderApp({
           // Skip the first license status, because that's already been used to determine
           // whether to include Watcher.
           licenseStatus$: licensing.license$.pipe(skip(1), map(licenseToLicenseStatus)),
@@ -60,6 +71,11 @@ export class WatcherUIPlugin implements Plugin<void, void, Dependencies, any> {
           history,
           getUrlForApp: application.getUrlForApp,
         });
+
+        return () => {
+          docTitle.reset();
+          unmountAppCallback();
+        };
       },
     });