Fix SkTime::GetDateTime Posix implementation, add unit test.

tests/Time.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTime.h"
+#include "Test.h"
+
+// Sanity checks for the GetDateTime function.
+DEF_TEST(Time_GetDateTime, r) {
+    SkTime::DateTime dateTime;
+    SkTime::GetDateTime(&dateTime);
+
+    // TODO(future generation): update these values.
+    const uint16_t kMinimumSaneYear = 2014;
+    const uint16_t kMaximumSaneYear = 2064;
+    REPORTER_ASSERT(r, dateTime.fYear >= kMinimumSaneYear);
+    REPORTER_ASSERT(r, dateTime.fYear <= kMaximumSaneYear);
+
+    REPORTER_ASSERT(r, dateTime.fMonth >= 1);
+    REPORTER_ASSERT(r, dateTime.fMonth <= 12);
+
+    REPORTER_ASSERT(r, dateTime.fDay >= 1);
+    REPORTER_ASSERT(r, dateTime.fDay <= 31);
+
+    REPORTER_ASSERT(r, dateTime.fHour <= 23);
+
+    REPORTER_ASSERT(r, dateTime.fMinute <= 59);
+
+    REPORTER_ASSERT(r, dateTime.fSecond <= 60);  // leap seconds are 23:59:60
+}