Fix crash due to parsing of raw branch code from Google Update

We should not return the raw Google Update branch code if we fail to determine what branch we are on. We should just assume stable.

We should also not add the branch code information to the version string, since it needs to be parsable by Version object. If we append the raw branch code, it might contain dots, which confuses the parsing done by the Version object.

BUG=31772
TEST=Change your branch code to something like 3.0-dev or 2.0-dev-somerandomstring. Chrome should not crash when you open the About box.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=35763

[Erik does not do reviews, 2010-01-07 23:50:51]

LGTM

http://codereview.chromium.org/523151/diff/1/4
File chrome/common/platform_util_win.cc (right):

http://codereview.chromium.org/523151/diff/1/4#newcode165
chrome/common/platform_util_win.cc:165: std::wstring update_branch = L"stable"; 
// The default if we get confused.
per mark's comment, this shouldn't be the default (and it always gets clobbered
anyway).

http://codereview.chromium.org/523151/diff/1/4#newcode199
chrome/common/platform_util_win.cc:199: update_branch = L"";
Add a comment here about why we don't return "stable" (per mark's info).