Use mojo for WebappRegistry.

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index b20e532d41d409a57e9ea5d1ce1efa3badaf6322..5423ad07b38dbe4ea91e88df6e5f1b451312c390 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -9,6 +9,7 @@ import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
 import("//media/media_options.gni")
+import("//mojo/public/tools/bindings/mojom.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 # //build/config/android/rules.gni imports //tools/grit/grit_rule.gni, which
@@ -773,6 +774,7 @@ split_static_library("browser") {
       ":client_discourse_context_proto",
       ":delta_file_proto",
       ":jni_headers",
+      ":webapp_registry_mojom",
       "//blimp/client/public",
       "//components/data_usage/android",
       "//components/precache/content",
@@ -994,6 +996,12 @@ if (android_java_ui) {
       "android/proto/delta_file.proto",
     ]
   }
+
+  mojom("webapp_registry_mojom") {
+    sources = [
+      "android/webapps/webapp_registry.mojom",
+    ]
+  }
 }
 
 if (is_win) {