lockPixels before calling getColorTable.

Fixes a bug where we try to dereference a NULL pointer.

Update the comment for SkBitmap::getColorTable, telling
the client that pixels must be locked for it to return
non-NULL.

R=edisonn@google.com

Review URL: https://codereview.chromium.org/15002002

git-svn-id: http://skia.googlecode.com/svn/trunk/include@9018 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed