chore: Add currency conversion telemetry (#26876)

## **Description**

In order to figure out which currencies we should support 24hr % change,
we need to know which currencies are the most popular.

Adds currency change dropdown event to telemetry events.

[![Open in GitHub
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## **Related issues**

Fixes: https://consensyssoftware.atlassian.net/browse/MMASSETS-344

## **Screenshots/Recordings**

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

app/scripts/controllers/metametrics.js

@@ -837,6 +837,7 @@ export default class MetaMetricsController {
         metamaskState.useTokenDetection,
       [MetaMetricsUserTrait.UseNativeCurrencyAsPrimaryCurrency]:
         metamaskState.useNativeCurrencyAsPrimaryCurrency,
+      [MetaMetricsUserTrait.CurrentCurrency]: metamaskState.currentCurrency,
       ///: BEGIN:ONLY_INCLUDE_IF(build-mmi)
       [MetaMetricsUserTrait.MmiExtensionId]: this.extension?.runtime?.id,
       [MetaMetricsUserTrait.MmiAccountAddress]: mmiAccountAddress,

shared/constants/metametrics.ts

@@ -468,6 +468,10 @@ export enum MetaMetricsUserTrait {
   MmiIsCustodian = 'mmi_is_custodian',
   ///: END:ONLY_INCLUDE_IF
   PetnameAddressCount = 'petname_addresses_count',
+  /**
+   * Identified when the user selects a currency from settings
+   */
+  CurrentCurrency = 'current_currency',
 }
 
 /**
@@ -514,6 +518,7 @@ export enum MetaMetricsEventName {
   BridgeLinkClicked = 'Bridge Link Clicked',
   BitcoinSupportToggled = 'Bitcoin Support Toggled',
   BitcoinTestnetSupportToggled = 'Bitcoin Testnet Support Toggled',
+  CurrentCurrency = 'Current Currency',
   DappViewed = 'Dapp Viewed',
   DecryptionApproved = 'Decryption Approved',
   DecryptionRejected = 'Decryption Rejected',

ui/pages/settings/settings-tab/settings-tab.component.js

@@ -119,7 +119,16 @@ export default class SettingsTab extends PureComponent {
               id="select-currency"
               options={currencyOptions}
               selectedOption={currentCurrency}
-              onChange={(newCurrency) => setCurrentCurrency(newCurrency)}
+              onChange={(newCurrency) => {
+                setCurrentCurrency(newCurrency);
+                this.context.trackEvent({
+                  category: MetaMetricsEventCategory.Settings,
+                  event: MetaMetricsEventName.CurrentCurrency,
+                  properties: {
+                    current_currency: newCurrency,
+                  },
+                });
+              }}
             />
           </div>
         </div>