Generate IDs for --load-extension by hashing the path instead

Generate IDs for --load-extension by hashing the path instead
of incrementing a static counter.

BUG=21281
TEST=Load an unpacked extension from chrome://extensions/ that
does not have an ID in its manifest. The resulting ID should
be random-looking, not something like "aaaaaa".

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=28095

[Matt Perry, 2009-10-05 17:32:15]

http://codereview.chromium.org/256049/diff/1/5
File chrome/browser/extensions/extensions_service_unittest.cc (right):

http://codereview.chromium.org/256049/diff/1/5#newcode1216
Line 1216: // If we reload the same path, we should get the same extension ID.
You don't seem to actually be testing this. I think you want to add a
ASSERT_EQ(loaded_[0]->id(), id_from_previous_load);

http://codereview.chromium.org/256049/diff/1/6
File chrome/common/extensions/extension.cc (right):

http://codereview.chromium.org/256049/diff/1/6#newcode624
Line 624: } else {
Can an extension ever have neither a path nor a public key?

[Aaron Boodman, 2009-10-05 20:04:48]

http://codereview.chromium.org/256049/diff/1/5
File chrome/browser/extensions/extensions_service_unittest.cc (right):

http://codereview.chromium.org/256049/diff/1/5#newcode1216
Line 1216: // If we reload the same path, we should get the same extension ID.
On 2009/10/05 17:32:15, Matt Perry wrote:
> You don't seem to actually be testing this. I think you want to add a
> ASSERT_EQ(loaded_[0]->id(), id_from_previous_load);

Fair enough. Done.

http://codereview.chromium.org/256049/diff/1/6
File chrome/common/extensions/extension.cc (right):

http://codereview.chromium.org/256049/diff/1/6#newcode624
Line 624: } else {
On 2009/10/05 17:32:15, Matt Perry wrote:
> Can an extension ever have neither a path nor a public key?

Ok, per our discussion, I've removed the default constructor.

[Matt Perry, 2009-10-05 20:55:39]

Cool. lgtm