GitLab

-   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