Implement SkAshmemDiscardableMemory

tests/DiscardableMemoryTest.cpp

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkDiscardableMemory.h"
+
+#include "Test.h"
+#include "TestClassDef.h"
+
+DEF_TEST(DiscardableMemory, reporter) {
+    const char testString[] = "HELLO, WORLD!";
+    const size_t len = sizeof(testString);
+    SkAutoTDelete<SkDiscardableMemory> dm(SkDiscardableMemory::Create(len));
+    REPORTER_ASSERT(reporter, dm.get() != NULL);
+    if (NULL == dm.get()) {
+        return;
+    }
+    void* ptr = dm->data();
+    REPORTER_ASSERT(reporter, ptr != NULL);
+    memcpy(ptr, testString, sizeof(testString));
+    dm->unlock();
+    bool success = dm->lock();
+    REPORTER_ASSERT(reporter, success);
+    if (!success) {
+        return;
+    }
+    ptr = dm->data();
+    REPORTER_ASSERT(reporter, 0 == memcmp(ptr, testString, len));
+    dm->unlock();
+}
+