Implement SkAshmemDiscardableMemory

-   Implement ashmem-backed SkDiscardableMemory subclass:
    This class in only accesible via the SkDiscardableMemory::Create()
    function, which replaces the mock implementation in
    SkDiscardableMemory_none.cpp

-   Added SkDiscardableMemory_ashmem.cpp to the Android port of Skia
    Removed SkDiscardableMemory_none.cpp from the Android port.

-   Added DiscardableMemoryTest.
    Still needs work.

-   SkDiscardablePixelRef Bugfix:
    onLockPixels() now calls SkDELETE on the SkDiscardableMemory pointer
    when it fails to unlock.

-   Improved documentation inside ashmem.h

BUG=
R=scroggo@google.com

Review URL: https://codereview.chromium.org/83563002

git-svn-id: http://skia.googlecode.com/svn/trunk@12608 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 34 insertions, 0 deletions

diff --git a/tests/DiscardableMemoryTest.cpp b/tests/DiscardableMemoryTest.cpp
new file mode 100644
index 0000000000..1fbc28478f
--- /dev/null
+++ b/tests/DiscardableMemoryTest.cpp
@@ -0,0 +1,34 @@
+/*
+ * 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();
+}
+