Replace SkFunction with std::function

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 void test_add_five(skiatest::Reporter* r, SkFunction<int(int)>&& f) { test_add_five(r, f); }
-
-static int add_five(int x) { return x + 5; }
-
-struct AddFive {
-    int operator()(int x) const { return x + 5; };
-};
-
-class MoveOnlyThree : SkNoncopyable {
-public:
-    MoveOnlyThree() {}
-    MoveOnlyThree(MoveOnlyThree&&) {}
-    MoveOnlyThree& operator=(MoveOnlyThree&&) { return *this; }
-
-    int val() { return 3; }
-};
-
-DEF_TEST(Function, r) {
-    // We should be able to turn a function pointer, an explicit functor, or a
-    // lambda into an SkFunction all equally well.
-    test_add_five(r, &add_five);
-    test_add_five(r, AddFive());
-    test_add_five(r, [](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, [&](int x) { return x + a + b + c + d + e; });
-
-    // Makes sure we forward arguments when calling SkFunction.
-    SkFunction<int(int, MoveOnlyThree&&, int)> f([](int x, MoveOnlyThree&& three, int y) {
-            return x * three.val() + y;
-    });
-    REPORTER_ASSERT(r, f(2, MoveOnlyThree(), 4) == 10);
-
-    // SkFunctions can go in containers.
-    SkTArray<SkFunction<int(int)>> add_fivers;
-    add_fivers.push_back(&add_five);
-    add_fivers.push_back(AddFive());
-    add_fivers.push_back([](int x) { return x + 5; });
-    add_fivers.push_back([&](int x) { return x + a + b + c + d + e; });
-    for (auto& f : add_fivers) {
-        test_add_five(r, f);
-    }
-
-    // SkFunctions are assignable.
-    SkFunction<int(int)> empty;
-    empty = [](int x) { return x + 5; };
-    test_add_five(r, empty);
-
-    // This all is silly acrobatics, but it should at least work correctly.
-    SkFunction<int(int)> emptyA, emptyB(emptyA);
-    emptyA = emptyB;
-    emptyA = emptyA;
-}