Choose memset procs once.

Choose memset procs once.

TSAN shows us racing on the function pointers.  Might as well fix it.

WARNING: ThreadSanitizer: data race (pid=19995)
  Read of size 8 at 0x7f703affb048 by thread T12 (mutexes: write M2957):
    #0 SkBitmap::internalErase(SkIRect const&, unsigned int, unsigned int, unsigned int, unsigned int) const /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/src/core/SkBitmap.cpp:886 (tests+0x0000003511ca)
    #1 SkBitmap::eraseARGB(unsigned int, unsigned int, unsigned int, unsigned int) const /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/src/core/SkBitmap.cpp:919 (tests+0x0000003534bf)
    #2 (anonymous namespace)::DecodingImageGenerator::getPixels(SkImageInfo const&, void*, unsigned long) /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/src/images/SkDecodingImageGenerator.cpp:195 (tests+0x00000051bee1)
    #3 SkDiscardablePixelRef::onNewLockPixels(SkPixelRef::LockRec*) /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/src/lazy/SkDiscardablePixelRef.cpp:63 (tests+0x00000039ad9c)
    #4 SkPixelRef::lockPixels(SkPixelRef::LockRec*) /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/src/core/SkPixelRef.cpp:179 (tests+0x0000003fec23)
    #5 SkBitmap::lockPixels() const /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/src/core/SkBitmap.cpp:414 (tests+0x00000034e41e)
    #6 SkAutoLockPixels /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/include/core/SkBitmap.h:819 (tests+0x0000002752f3)
    #7 ImageDecoderOptions(skiatest::Reporter*) /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/tests/ImageDecodingTest.cpp:565 (tests+0x000000275d03)
    #8 skiatest::Test::run() /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/tests/Test.cpp:107 (tests+0x0000002263e7)
    #9 SkTestRunnable::run() /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/tests/skia_test.cpp:108 (tests+0x0000001d8607)
    #10 SkThreadPoolPrivate::ThreadLocal<void>::run(SkTRunnable<void>*) /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/include/utils/SkThreadPool.h:108 (tests+0x0000001d817e)
    #11 thread_start(void*) /var/scratch/Release/../../../usr/local/google/home/mtklein/skia/src/utils/SkThreadUtils_pthread.cpp:66 (tests+0x000000604347)

  Previous write of size 8 at 0x7f703affb048 by thread T26:
    [failed to restore the stack]


BUG=skia:1792
Committed: http://code.google.com/p/skia/source/detail?r=14548

[bungeman-skia, 2014-04-24 20:44:18]

lgtm

[mtklein, 2014-04-24 20:44:38]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-04-24 20:45:11]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/250503003/1

[commit-bot: I haz the power, 2014-04-24 20:45:14]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-04-24 20:45:15]

Presubmit check for 250503003-1 failed and returned exit status 1.

Running presubmit commit checks ...

** Presubmit ERRORS **
Since the CL is editing public API, you must have an LGTM from one of:
('reed@chromium.org', 'reed@google.com', 'bsalomon@chromium.org',
'bsalomon@google.com')

[reed1, 2014-05-02 20:11:33]

lgtm

[mtklein, 2014-05-02 20:16:19]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-05-02 20:16:30]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/250503003/1

[commit-bot: I haz the power, 2014-05-02 20:28:58]

Change committed as 14548