[DevTools] Add recorder experiment

Bug: chromium:1144127
Change-Id: I2fc34e51d9f6f36b3fa71f64e745b1d30bec2c68
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2509579
Auto-Submit: Jan Scheffler <janscheffler@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822630}

tools/metrics/histograms/enums.xml

@@ -16580,6 +16580,7 @@ metrics consent we also won't be able to send UMA metrics. -->
   <int value="35" label="keyboardShortcutEditor"/>
   <int value="36" label="cssFlexboxFeatures"/>
   <int value="37" label="showWebVitalsInPerformancePanel"/>
+  <int value="38" label="recorder"/>
 </enum>
 
 <enum name="DevToolsGridOverlayOpenedFrom">