Write out useful Android GN vars in a non-gradle-specific form.

build/android/BUILD.gn

Index: build/android/BUILD.gn
diff --git a/build/android/BUILD.gn b/build/android/BUILD.gn
index e483048f744c91468967924c81a8266d36cdc58f..09ae4a2ecc46e9a345ff2013a2245a3858dc5c56 100644
--- a/build/android/BUILD.gn
+++ b/build/android/BUILD.gn
@@ -41,17 +41,17 @@ if (enable_java_templates) {
     output_jar = "$root_out_dir/lib.java/android.interface.jar"
   }
 
-  _rebased_android_sdk_root = rebase_path(android_sdk_root, root_build_dir)
-
-  # Record GN vars that are needed by generate_gradle.py.
-  # One statement per-line to make GN's formatter leave it alone.
+  # Write to a file some GN vars that are useful to scripts that use the output
+  # directory. Format is chosen as easliy importable by both python and bash.
   CR = "$0x0A"
-  _json = "{$CR"
-  _json += "  \"android_sdk_root\": \"$_rebased_android_sdk_root\",$CR"
-  _json += "  \"compile_sdk_version\": \"$android_sdk_version\",$CR"
-  _json += "  \"build_tools_version\": \"$android_sdk_build_tools_version\"$CR"
-  _json += "}$CR"
-  write_file("$root_build_dir/gradle/config.json", _json)
+  _data = ""
+  _data += "android_sdk_build_tools=" +
+           rebase_path(android_sdk_build_tools, root_build_dir) + CR
+  _data += "android_sdk_build_tools_version=$android_sdk_build_tools_version$CR"
+  _data +=
+      "android_sdk_root=" + rebase_path(android_sdk_root, root_build_dir) + CR
+  _data += "android_sdk_version=$android_sdk_version$CR"
+  write_file("$root_build_dir/build_vars.txt", _data)
 }
 
 # Copy to the lib.unstripped directory so that gdb can easily find it.