Add metric to HttpEngine preload

See the other CLs in the same topic for the details.

Test: See other CL
Bug: 380349437
Change-Id: I4b936e3d834462bba5a368d6dd1a1e262c17f0c9

framework/Android.bp

@@ -160,7 +160,10 @@ java_library {
 java_defaults {
     name: "CronetJavaDefaults",
     srcs: [":httpclient_api_sources"],
-    static_libs: ["com.android.net.http.flags-aconfig-java"],
+    static_libs: [
+        "com.android.net.http.flags-aconfig-java",
+        "modules-utils-expresslog",
+    ],
     libs: [
         "androidx.annotation_annotation",
     ],