small-object optimization for SkFunction

tests/FunctionTest.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFunction.h"
 #include "Test.h"
 
 static void test_add_five(skiatest::Reporter* r, SkFunction<int(int)>&& f) {
+    REPORTER_ASSERT(r, f(3) == 8);
     REPORTER_ASSERT(r, f(4) == 9);
 }
 
 static int add_five(int x) { return x + 5; }
 
 struct AddFive {
     int operator()(int x) { return x + 5; };
 };
 
 DEF_TEST(Function, r) {
     // We should be able to turn a static function, an explicit functor, or a lambda
     // all into an SkFunction equally well.
     test_add_five(r, SkFunction<int(int)>(&add_five));
     test_add_five(r, SkFunction<int(int)>(AddFive()));
     test_add_five(r, SkFunction<int(int)>([](int x) { return x + 5; }));
+
+    // AddFive and the lambda above are both small enough to test small-object optimization.
+    // Now test a lambda that's much too large for the small-object optimization.
+    int a = 1, b = 1, c = 1, d = 1, e = 1;
+    test_add_five(r, SkFunction<int(int)>([&](int x) { return x + a + b + c + d + e; }));
 }