When looking up a file in the first IDs list, and the file is outside of the tree starting at SRCDI…

When looking up a file in the first IDs list, and the file is outside of the tree starting at SRCDIR, just use the filename as key

BUG=none
TEST=building content_shell from within WebKit works for Release mode
Committed: https://code.google.com/p/grit-i18n/source/detail?r=58

[jochen (gone - plz use gerrit), 2012-07-23 13:12:15]

please review

The issue I have is that in chromium's resource_ids file, there's a key
<(SHARED_INTERMEDIATE_DIR)/devtools/devtools_resources.grd.
SHARED_INTERMEDIATE_DIR is a relative path, and when building chrome, this path
is indeed also relative to the SRCDIR defined in the resource_ids file.

When building WebKit, however, the SHARED_INTERMEDIATE_DIR is relative to
WebKit's root, and so the key resulting for replacing SHARED_INTERMEDIATE_DIR
doesn't make sense anymore.

I managed to work around by adding devtools_resources.grd as key. It turns out,
however, that just worked because my WebKit output directory for a debug build
had the correct size, so chopping of len(src_root_dir)+1 characters from the
absolute path resulted in devtools_resources.grd. When you do a Release build,
the path length is different, and so the key is not found.

Instead of relying on the path lengths, I introduced an explicit check: If the
file is outside of src_root_dir, just use the filename as key.