The dependency on https://code.google.com/p/chromium/codesearch#chromium/src/build/util/version.gypi (which in turn requires a file chrome/VERSION) in Chromium's https://code.google.com/p/chromium/codesearch#chromium/src/build/isolate.gypi makes it hard to reuse this for client projects.

One might argue that client projects shouldn't depend on these things, but from WebRTC's perspective, we've historically been using the Chromium Android test toolchain via https://code.google.com/p/chromium/codesearch#chromium/src/testing/android/native_test.gyp. It's been working well for us until we now started implementing swarming support.
For Android, we get the problem via https://code.google.com/p/chromium/codesearch#chromium/src/base/base.gyp&l=1662, which is loaded when you depend on native_test.gyp.

One workaround for now is to create a dummy chrome/VERSION, but ideally the version stuff shouldn't need to be in the isolate.gypi.
If the version_full variable needs to be passed, maybe it can just have a default value in isolate.gypi instead and be set outside of isolate.gypi instead, for the use cases that needs it.

It seems it was added in https://codereview.chromium.org/140263002 to be able to run chrome.exe on Windows...