Fix for Android ClipCache unit test crash

The surface cause of the crash was my failure to check the pointer returned from createUncachedTexture. The deeper cause of the crash was that the nexus s doesn't seem to support any single channel texture formats.

[DerekS, 2012-05-10 19:50:53]

Brian may want to look at this as he knows more about this code than I do, but
lgtm.

[bsalomon, 2012-05-10 19:55:16]

http://codereview.appspot.com/6199063/diff/1/tests/ClipCacheTest.cpp
File tests/ClipCacheTest.cpp (right):

http://codereview.appspot.com/6199063/diff/1/tests/ClipCacheTest.cpp#newcode25
tests/ClipCacheTest.cpp:25: desc.fConfig    = kRGBA_8888_UPM_GrPixelConfig;
Was UPM chosen for any particular reason? It's a weirdo format for us. The
normal one is kSkia8888_PM_GrPixelConfig.

[robertphillips, 2012-05-10 20:36:16]

http://codereview.appspot.com/6199063/diff/1/tests/ClipCacheTest.cpp
File tests/ClipCacheTest.cpp (right):

http://codereview.appspot.com/6199063/diff/1/tests/ClipCacheTest.cpp#newcode25
tests/ClipCacheTest.cpp:25: desc.fConfig    = kRGBA_8888_UPM_GrPixelConfig;
On 2012/05/10 19:55:16, bsalomon wrote:
> Was UPM chosen for any particular reason? It's a weirdo format for us. The
> normal one is kSkia8888_PM_GrPixelConfig.

Done.

[bsalomon, 2012-05-10 21:01:23]

On 2012/05/10 20:36:16, robertphillips wrote:
> http://codereview.appspot.com/6199063/diff/1/tests/ClipCacheTest.cpp
> File tests/ClipCacheTest.cpp (right):
> 
> http://codereview.appspot.com/6199063/diff/1/tests/ClipCacheTest.cpp#newcode25
> tests/ClipCacheTest.cpp:25: desc.fConfig    = kRGBA_8888_UPM_GrPixelConfig;
> On 2012/05/10 19:55:16, bsalomon wrote:
> > Was UPM chosen for any particular reason? It's a weirdo format for us. The
> > normal one is kSkia8888_PM_GrPixelConfig.
> 
> Done.

LGTM

[robertphillips, 2012-05-10 21:27:09]

committed as r3902