Adding a unique runtime Id to Profile objects, that can be used as the key...

Adding a unique runtime Id to Profile objects, that can be used as the key
of the ProfileSiteInstanceMap type.  This is used to make sure that Profile
objects can correctly share site information when one profile is derived
from another.

BUG=0
TEST=See unit tests

[amit, 2009-10-06 18:44:56]

Thanks Roger for implementing this. LGTM with a nit.

http://codereview.chromium.org/255087/diff/1001/1004
File chrome/browser/browsing_instance.h (right):

http://codereview.chromium.org/255087/diff/1001/1004#newcode105
Line 105: typedef base::hash_map<int, SiteInstanceMap> ProfileSiteInstanceMap;
int and runtime id may have different sizes. How about:
typedef void* ProfileId;

[NOT FOR CODE REVIEWS, 2009-10-06 20:10:26]

Thanks Amit.  Your comment is addressed, changes uploaded.  Please see most
recent patch set.  If all is OK with you, can you please commit for me?  Thanks.

[amit, 2009-10-06 21:08:15]

lgrm with a nit

http://codereview.chromium.org/255087/diff/2002/6004
File chrome/browser/browsing_instance.cc (right):

http://codereview.chromium.org/255087/diff/2002/6004#newcode57
Line 57: : reinterpret_cast<ProfileId>(0);
If we have a NULL profile then should be be returning a valid site instance? If
yes then maybe we can replace reinterpret_cast<ProfileId>(0) with
Profile::InvalidProfileId?