digitalgoods: Add kDigitalGoodsListPurchases for measuring new method.

Bug: 1139795
Change-Id: I47f90b0949cfdde8b11f7ed8bc22091fd8b16168
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2494188
Commit-Queue: Glen Robertson <glenrob@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820666}

third_party/blink/public/mojom/web_feature/web_feature.mojom

@@ -3037,6 +3037,7 @@ enum WebFeature {
   kUnicodeBidiPlainText = 3706,
   kColorSchemeDarkSupportedOnRoot = 3707,
   kWebBluetoothGetAvailability = 3708,
+  kDigitalGoodsListPurchases = 3709,
 
   // Add new features immediately above this line. Don't change assigned
   // numbers of any item, and don't reuse removed slots.

tools/metrics/histograms/enums.xml

@@ -30005,6 +30005,7 @@ Called by update_use_counter_feature_enum.py.-->
   <int value="3706" label="UnicodeBidiPlainText"/>
   <int value="3707" label="ColorSchemeDarkSupportedOnRoot"/>
   <int value="3708" label="WebBluetoothGetAvailability"/>
+  <int value="3709" label="DigitalGoodsListPurchases"/>
 </enum>
 
 <enum name="FeaturePolicyAllowlistType">