Add thread-per-core setting to SkThreadPool.

tests/skia_test.cpp

Index: tests/skia_test.cpp
diff --git a/tests/skia_test.cpp b/tests/skia_test.cpp
index 6330b326a883a6cb26551ca4f985571c144410f7..20527b0ad70720d8c5f4c40db39197dbb8469312 100644
--- a/tests/skia_test.cpp
+++ b/tests/skia_test.cpp
@@ -141,8 +141,8 @@ DEFINE_string2(resourcePath, i, NULL, "directory for test resources.");
 DEFINE_bool2(extendedTest, x, false, "run extended tests for pathOps.");
 DEFINE_bool2(threaded, z, false, "allow tests to use multiple threads internally.");
 DEFINE_bool2(verbose, v, false, "enable verbose output.");
-DEFINE_int32(threads, 8,
-             "If >0, run threadsafe tests on a threadpool with this many threads.");
+DEFINE_int32(threads, SkThreadPool::kThreadPerCore,
+             "Run threadsafe tests on a threadpool with this many threads.");
 
 // Deletes self when run.
 class SkTestRunnable : public SkRunnable {