Revert 147988 - Upgrade AlignedMemory to support dynamic allocations.

Revert 147988 - Upgrade AlignedMemory to support dynamic allocations.

Adds two new methods: AlignedAlloc and AlignedFree for creating and
destroying dynamic aligned allocations respectively.  Also adds a
helper class, ScopedPtrAlignedFree, for use with scoped_ptr_malloc.

AlignedAlloc uses posix_memalign for OS X (now that we're targeting
10.6), Linux and _aligned_alloc() on Windows.  Android and NaCl use
memalign() since they do not expose posix_memalign() and memalign()
is safe to use with free() on those platforms.

Also hacks around a bug in Visual C++ where __alignof will sometimes
return zero:
http://connect.microsoft.com/VisualStudio/feedback/details/682695/c-alignof-fails-to-properly-evalute-alignment-of-dependent-types

BUG=none
TEST=base_unittests + new test, trybots.

Review URL: https://chromiumcodereview.appspot.com/10796020

TBR=dalecurtis@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=148016