Add chunk heap, use it for gralloc buffers

Rather than allocating buffers solely from system memory
we will now attempt to first allocate them out of a specific
graphics carveout.  If there isn't space for a buffer in the
carveout the system heap will be used instead.

Change-Id: I30844123910209a0201c9462fb4776f123537e50
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
3 files changed