Change webapk packages and directory structure

webapk/libs/common/BUILD.gn

Index: webapk/libs/common/BUILD.gn
diff --git a/third_party/haha/BUILD.gn b/webapk/libs/common/BUILD.gn
similarity index 55%
copy from third_party/haha/BUILD.gn
copy to webapk/libs/common/BUILD.gn
index 6e7a2626e4f6b8d130d775c4a7c6c9d0d7bd8a50..8381ae5132765cb859f1a78201a693aee313d334 100644
--- a/third_party/haha/BUILD.gn
+++ b/webapk/libs/common/BUILD.gn
@@ -4,6 +4,9 @@
 
 import("//build/config/android/rules.gni")
 
-android_java_prebuilt("haha") {
-  jar_path = "haha-2.0.2.jar"
+android_library("common") {
+  java_files = [
+    "src/org/chromium/webapk/lib/common/WebApkConstants.java",
+    "src/org/chromium/webapk/lib/common/WebApkUtils.java",
+  ]
 }