Android: Move UkmUtilsForTest.java.

Moved to a subdirectory of the build target using it. The old location
was confusing because it's in the same directory as non test code.

Bug: 1010218
Change-Id: I1de7cd4ec72c7967506ebd8451fcf2b9378a9fe3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1838522
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702581}

chrome/browser/android/metrics/BUILD.gn

@@ -5,6 +5,9 @@
 if (is_android) {
   import("//build/config/android/rules.gni")
 
+  _jni_java_files =
+      [ "javatests/org/chromium/chrome/metrics/util/UkmUtilsForTest.java" ]
+
   static_library("ukm_utils_for_test") {
     testonly = true
     sources = [
@@ -19,14 +22,12 @@ if (is_android) {
   }
 
   generate_jni("jni_headers") {
-    sources = [
-      "../../../android/java/src/org/chromium/chrome/browser/metrics/UkmUtilsForTest.java",
-    ]
+    sources = _jni_java_files
   }
 
   android_library("ukm_utils_java") {
     testonly = true
-    java_files = [ "../../../android/java/src/org/chromium/chrome/browser/metrics/UkmUtilsForTest.java" ]
+    java_files = _jni_java_files
     deps = [
       "//base:base_java",
     ]