digitalgoods:Enable on supported platforms only.

This prevents DG from being enabled by
"experimental-web-platform-features" on unsupported platforms, which
would crash the tab because there is no mojo impl on those platforms.

Bug: 1142730,1131747
Change-Id: I00058b04dc98fe4032d0b8108059ecc08a892ae0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2526891Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Auto-Submit: Glen Robertson <glenrob@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826045}

third_party/blink/renderer/modules/payments/goods/dom_window_digital_goods.cc

@@ -57,7 +57,6 @@ ScriptPromise DOMWindowDigitalGoods::GetDigitalGoodsService(
     return promise;
   }
 
-  // TODO: Bind only on platforms where an implementation exists.
   if (!mojo_service_) {
     ExecutionContext::From(script_state)
         ->GetBrowserInterfaceBroker()

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -701,7 +701,13 @@
       name: "DigitalGoods",
       origin_trial_feature_name: "DigitalGoods",
       origin_trial_os: ["android"],
-      status: "experimental",
+      status: {
+        "Android": "experimental",
+        "ChromeOS": "experimental",
+        // crbug.com/1143079: Web tests cannot differentiate ChromeOS and Linux,
+        // so enable the API on all platforms for testing.
+        "default": "test"
+      },
     },
     {
       name: "DirectSockets",