gn: Generalize process_version() and move it to build/util (take #2)

components/cronet/android/BUILD.gn

Index: components/cronet/android/BUILD.gn
diff --git a/components/cronet/android/BUILD.gn b/components/cronet/android/BUILD.gn
index 34a58bf7b3a456857a7c083c3421653a148e33d2..2e9b57997a0cf157dfabaa58590ae8ed012c3576 100644
--- a/components/cronet/android/BUILD.gn
+++ b/components/cronet/android/BUILD.gn
@@ -5,8 +5,8 @@
 import("//build/buildflag_header.gni")
 import("//build/config/android/config.gni")
 import("//build/config/android/rules.gni")
+import("//build/util/process_version.gni")
 import("//build/util/version.gni")
-import("//chrome/version.gni")
 import("//testing/test.gni")
 import("//third_party/protobuf/proto_library.gni")
 import("//url/features.gni")
@@ -95,6 +95,10 @@ _generated_api_version_java =
 
 process_version("cronet_api_version_java") {
   template_file = "api/src/org/chromium/net/ApiVersion.template"
+  sources = [
+    "//build/util/LASTCHANGE",
+    "//chrome/VERSION",
+  ]
   output = _generated_api_version_java
 }
 
@@ -116,6 +120,10 @@ _generated_impl_version_java =
 
 process_version("cronet_impl_version_java") {
   template_file = "java/src/org/chromium/net/impl/ImplVersion.template"
+  sources = [
+    "//build/util/LASTCHANGE",
+    "//chrome/VERSION",
+  ]
   output = _generated_impl_version_java
 }