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

chrome/installer/linux/BUILD.gn

Index: chrome/installer/linux/BUILD.gn
diff --git a/chrome/installer/linux/BUILD.gn b/chrome/installer/linux/BUILD.gn
index 9b71c46fcdfb257373e1b80ea232c498b76d1da3..e2f03793a5f8406984ea2ebe4214f8adbef1b29a 100644
--- a/chrome/installer/linux/BUILD.gn
+++ b/chrome/installer/linux/BUILD.gn
@@ -5,8 +5,9 @@
 import("//build/config/chrome_build.gni")
 import("//build/config/features.gni")
 import("//build/config/sanitizers/sanitizers.gni")
+import("//build/util/process_version.gni")
 import("//build/util/version.gni")
-import("//chrome/version.gni")
+import("//chrome/process_version_rc_template.gni")  # For branding_file_path.
 
 if (current_cpu == "x86" || current_cpu == "x64") {
   import("//media/cdm/ppapi/cdm_paths.gni")
@@ -150,6 +151,10 @@ if (!is_chromeos) {
 process_version("save_build_info") {
   # Just output the default version info variables (no template).
   process_only = true
+  sources = [
+    "//chrome/VERSION",
+    branding_file_path,
+  ]
   output = "$root_out_dir/installer/version.txt"
 }