Partial fix for Skia issue 1769: GenerateGMs crashing (out of memory)

Partial fix for Skia issue 1769: GenerateGMs crashing (out of memory)

GenerateGMs was crashing because we were adding genID listeners for
textures even when creation failed -- in this case the key generated
is not valid, so when it comes time to purge it, it triggers an
assert and then an apparent crash. The solution is to not add
a genID listener in this case.

This doesn't solve the problem of running out of memory, it just prevents it 
from causing a crash in Debug builds.

BUG=

Committed: http://code.google.com/p/skia/source/detail?r=12062

[mtklein, 2013-10-31 19:57:46]

On 2013/10/31 19:45:25, JimVV wrote:

lgtm

Ah, thank you.  My bad.

[bsalomon, 2013-10-31 19:58:49]

lgtm

[commit-bot: I haz the power, 2013-10-31 19:59:50]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/jvanverth@google.com/55023005/1

[robertphillips, 2013-10-31 20:00:20]

lgtm

[commit-bot: I haz the power, 2013-10-31 20:22:50]

Change committed as 12062