NSS's filesystem speed detection doesn't seem to work on Ubuntu Lucid....

NSS's filesystem speed detection doesn't work with the latest versions
of sqlite, such as 3.6.22.  Set the NSS_SDB_USE_CACHE environment
variable to "yes" to override NSS's detection if the database is on NFS.

Get rid of the USE_NSS_FOR_SSL_ONLY macro because it is simply the
opposite of USE_NSS.

Use EnvVarGetter to get and set environment variables.  Use FilePath
instead of std::string to represent path names.

R=thestig
BUG=48585
TEST=Run Chrome on Ubuntu Lucid with a home directory on "slow" NFS.
HTTPS connection setup shoud not be very slow.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=52379

[Lei Zhang, 2010-07-14 00:27:22]

http://codereview.chromium.org/2895015/diff/1/2
File base/nss_util.cc (right):

http://codereview.chromium.org/2895015/diff/1/2#newcode81
base/nss_util.cc:81: void UseLocalCacheOfNSSDatabaseIfNFS(const std::string
database_dir) {
It would be nice if we used FilePath here. There's lots of places in this file
that should be converted to FilePaths... gotta start somewhere.

http://codereview.chromium.org/2895015/diff/1/2#newcode86
base/nss_util.cc:86: if (getenv(use_cache_env_var) == NULL) {
Can you use base::EnvVarGetter instead of get/setenv directly?

[wtc, 2010-07-14 02:33:17]

thestig: thanks a lot for the review.  I made the changes you suggested.
Please review Patch Set 2.

[wtc, 2010-07-14 03:14:11]

thestig: Please review Patch Set 3.  I can't use AppendASCII to add an
absolute path to a FilePath, so I have to go back initializing FilePath with
'home', which is not ideal because FilePath::StringType is not std::string on
all platforms.

[Lei Zhang, 2010-07-14 04:53:21]

LGTM