fix: decoding_in_progress metric and flaky decoding_latency metri…

…cs tests (#29852)

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## **Description**

Fix: 
1. Unreachable `decoding_in_progress` metric when decoding is loading
  - Add metric when decoding is loading
2. Flaky `decoding_latency` metric test
  - Add faker timer

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## **Related issues**

Fixes: #29851
Fixes: #29509

## **Manual testing steps**

1. Go to this page...
2.
4.

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

Flaky test appearing locally:
![CleanShot 2025-01-21 at 17 38
18@2x](https://github.com/user-attachments/assets/970e8aed-8cf1-4e06-83fc-97d28d7e4835)


### **After**

<!-- [screenshots/recordings] -->

## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've completed the PR template to the best of my ability
- [ ] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/main/.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.

ui/pages/confirmations/hooks/useDecodedSignatureMetrics.test.ts

@@ -22,6 +22,18 @@ const decodingData: DecodingData = {
 };
 
 describe('useDecodedSignatureMetrics', () => {
+  /**
+   * Use fake timer since the tests test the decoding_latency value which is flaky.
+   * Without the fake timer, the value may show as 0 or 0.001.
+   */
+  beforeAll(() => {
+    jest.useFakeTimers({ now: 10 });
+  });
+
+  afterAll(() => {
+    jest.useRealTimers();
+  });
+
   it('should not call updateSignatureEventFragment if supportedByDecodingAPI is false', async () => {
     const state = getMockTypedSignConfirmStateForRequest({
       ...permitSignatureMsg,
@@ -43,7 +55,7 @@ describe('useDecodedSignatureMetrics', () => {
     expect(mockUpdateSignatureEventFragment).toHaveBeenCalledTimes(0);
   });
 
-  it('should not call updateSignatureEventFragment if decodingLoading is true', async () => {
+  it('calls updateSignatureEventFragment with "decoding_in_progress" if decoding is loading ', async () => {
     const state = getMockTypedSignConfirmStateForRequest({
       ...permitSignatureMsg,
       decodingLoading: true,
@@ -61,7 +73,12 @@ describe('useDecodedSignatureMetrics', () => {
       state,
     );
 
-    expect(mockUpdateSignatureEventFragment).toHaveBeenCalledTimes(0);
+    expect(mockUpdateSignatureEventFragment).toHaveBeenCalledTimes(1);
+    expect(mockUpdateSignatureEventFragment).toHaveBeenLastCalledWith({
+      properties: {
+        decoding_response: 'decoding_in_progress',
+      },
+    });
   });
 
   it('should call updateSignatureEventFragment with correct parameters if there are no state changes', async () => {

ui/pages/confirmations/hooks/useDecodedSignatureMetrics.ts

@@ -9,6 +9,7 @@ import { useSignatureEventFragment } from './useSignatureEventFragment';
 enum DecodingResponseType {
   Change = 'CHANGE',
   NoChange = 'NO_CHANGE',
+  InProgress = 'decoding_in_progress',
 }
 
 export function useDecodedSignatureMetrics(supportedByDecodingAPI: boolean) {
@@ -32,7 +33,17 @@ export function useDecodedSignatureMetrics(supportedByDecodingAPI: boolean) {
       : DecodingResponseType.NoChange);
 
   useEffect(() => {
-    if (decodingLoading || !supportedByDecodingAPI) {
+    if (!supportedByDecodingAPI) {
+      return;
+    }
+
+    if (decodingLoading) {
+      updateSignatureEventFragment({
+        properties: {
+          decoding_response: DecodingResponseType.InProgress,
+        },
+      });
+
       return;
     }
 
@@ -41,9 +52,7 @@ export function useDecodedSignatureMetrics(supportedByDecodingAPI: boolean) {
         decoding_change_types: decodingChangeTypes,
         decoding_description: decodingData?.error?.message ?? null,
         decoding_latency: loadingTime ?? null,
-        decoding_response: decodingLoading
-          ? 'decoding_in_progress'
-          : decodingResponse,
+        decoding_response: decodingResponse,
       },
     });
   }, [