Add latest changes from gitlab-org/gitlab@master

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diff --git a/doc/development/fe_guide/vue.md b/doc/development/fe_guide/vue.md
index 396467b47d1..2c624c9085e 100644
--- a/doc/development/fe_guide/vue.md
+++ b/doc/development/fe_guide/vue.md
@@ -104,6 +104,51 @@ document.addEventListener('DOMContentLoaded', () => new Vue({
 }));
 ```
 
+#### Accessing feature flags
+
+Use Vue's [provide/inject](https://vuejs.org/v2/api/#provide-inject) mechanism
+to make feature flags available to any descendant components in a Vue
+application. The `glFeatures` object is already provided in `commons/vue.js`, so
+only the mixin is required to utilize the flags:
+
+```javascript
+// An arbitrary descendant component
+
+import glFeatureFlagsMixin from '~/vue_shared/mixins/gl_feature_flags_mixin';
+
+export default {
+  // ...
+  mixins: [glFeatureFlagsMixin()],
+  // ...
+  created() {
+    if (this.glFeatures.myFlag) {
+      // ...
+    }
+  },
+}
+```
+
+This approach has a few benefits:
+
+- Arbitrarily deeply nested components can opt-in and access the flag without
+  intermediate components being aware of it (c.f. passing the flag down via
+  props).
+- Good testability, since the flag can be provided to `mount`/`shallowMount`
+  from `vue-test-utils` as easily as a prop.
+
+  ```javascript
+  import { shallowMount } from '@vue/test-utils';
+
+  shallowMount(component, {
+    provide: {
+      glFeatures: { myFlag: true },
+    },
+  });
+  ```
+
+- No need to access a global variable, except in the application's
+  [entry point](#accessing-the-gl-object).
+
 ### A folder for Components
 
 This folder holds all components that are specific of this new feature.