Fix error in one of the DesksSwitchSource enum labels

TBR=jamescook@chromium.org
BUG=none

Change-Id: I9a41e645cbd8e0e6a8cb275d387142174051dece
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2097238Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748976}

tools/metrics/histograms/enums.xml

@@ -14714,7 +14714,7 @@ to ensure that the crash string is shown properly on the user-facing crash UI.
   <int value="2" label="Desk-switch keyboard shortcut"/>
   <int value="3" label="Mini_view button press"/>
   <int value="4" label="Window on desk activated"/>
-  <int value="5" label="Desk-switch 3-finger touchpad swipe"/>
+  <int value="5" label="Desk-switch 4-finger touchpad swipe"/>
   <int value="6" label="User switch in a multi-profile session"/>
 </enum>