This seems a bit flaky, with some jobs passing and others failing.

https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/143785 for an example failure.

version.h.in seems to be the template that is causing issues in all examples I've looked at, but there are multiple different generated files having this failure.

ninja explain: recorded mtime of gen/extensions/shell/common/version.h older than most recent input ../../build/util/LASTCHANGE (545173957 vs 545174986)
ninja explain: gen/extensions/shell/common/version.h is dirty
ninja explain: obj/extensions/shell/version_header_action.stamp is dirty
ninja explain: obj/extensions/shell/version_header_action.stamp is dirty
ninja explain: gen/extensions/shell/common/version.h is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_content_client.obj is dirty
ninja explain: gen/extensions/shell/common/version.h is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_nacl_browser_delegate.obj is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_content_client.obj is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_nacl_browser_delegate.obj is dirty
ninja explain: app_shell_unittests.exe is dirty
ninja explain: obj/extensions/shell/version_header_action.stamp is dirty
ninja explain: obj/extensions/shell/version_header_action.stamp is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_content_client.obj is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_nacl_browser_delegate.obj is dirty
ninja explain: extensions_browsertests.exe is dirty
ninja explain: obj/extensions/shell/version_header_action.stamp is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_content_client.obj is dirty
ninja explain: obj/extensions/shell/app_shell_lib/shell_nacl_browser_delegate.obj is dirty
ninja explain: extensions_unittests.exe is dirty

extension/shell/OWNERS added to cc