fix display of filenames in file:/// URLs

fix display of filenames in file:/// URLs

(retry of previous code with tests fixed)

The code attempted to shorten file:/// URLs to just the filename
when displayed as the title of a page.  But that appears to have
regressed sometime in the past.  This shortening is consistent with
how we display the title of images (which are like "foo.png (123x456)".)
Chrome does a poor job of displaying longer titles (most of the
tab title ends up being "file:///C:/" anyway).

In any case, using a FilePath to get the filename from a URL may not
have even worked on Windows, where the path separator is a backslash.

It appears Glen wrote the original code, Brett may be the one to have
regressed it in a refactor, and I probably broke it worse in a FilePath
refactor.

BUG=69467
TEST=load a text file via a file: URL; tab title is just the file name

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=77008

[Glen Murphy, 2011-03-03 18:02:14]

Will this escape spaces in filenames (%20s)? If so, it LGTM.

[brettw, 2011-03-03 18:08:36]

Seems like it should be easy to write a unit test for this?

Also, what about directories?
file:///foo/bar/
I think your patch will return the empty string which is bad.

[Evan Martin, 2011-03-03 18:24:20]

On 2011/03/03 18:02:14, Glen Murphy wrote:
> Will this escape spaces in filenames (%20s)? If so, it LGTM.

Yes, we just above "format" the URL into something human-readable.

[Evan Martin, 2011-03-03 18:25:20]

On 2011/03/03 18:08:36, brettw wrote:
> Seems like it should be easy to write a unit test for this?

I knew it in my heart but didn't want to admit it.  I'll take a shot.

> Also, what about directories?
> file:///foo/bar/
> I think your patch will return the empty string which is bad.

Directories get the custom "index of foobar" title so this code doesn't seem to
affect it.

[Evan Martin, 2011-03-03 18:33:25]

Oh, sweet, we have a plain unit test for this code!  I was fearing I'd have to
add yet another flaky UI test for tab titles etc.

New patch up with a test amendment.

[brettw, 2011-03-03 18:45:20]

LGTM