Cherry-Picked the following commits:
0defd8f2 Changed "WebM" to "AOMedia" & "webm" to "aomedia"
54e66767 Replace "VPx" by "AVx"
5082a369 Change "Vpx" to "Avx"
7df44f17 Replace "Vp9" w/ "Av1"
967f722f Remove kVp9CodecId
828f30ce Change "Vp8" to "AOM"
030b5ffc AUTHORS regenerated
2524caee Add ref-mv experimental flag
016762be Change copyright notice to AOMedia form
81e55269 Replace vp9 w/ av1
9b94565b Add missing files
fa8ca9f2 Change "vp9" to "av1"
ec838b76  Convert "vp8" to "aom"
80edfa01 Change "VP9" to "AV1"
d1a11fb9 Change "vp8" to "aom"
7b582513 Point to WebM test data
dd1a5c8d Replace "VP8" with "AOM"
ff00fc0f Change "VPX" to "AOM"
01dee0bb Change "vp10" to "av1" in source code
cebe6f0c Convert "vpx" to "aom"
17b05679 rename vp10*.mk to av1_*.mk
fe5f8a8a rename files vp10_* to av1_*

Change-Id: I6fc3d18eb11fc171e46140c836ad5339cf6c9419

Manually cherry-picked commits:
ceef0583 libvpx->libaom part2
3d26d916 libvpx -> libaom
cfea7dd7 vp10/ -> av1/
3a8eff73 Fix a build issue for a test
bf4202ed Rename vpx to aom

Change-Id: I1b0eb5a40796e3aaf41c58984b4229a439a597dc

Change-Id: Ibc7933fba85feeb30ef9b14b302d932aff19f54e

Change-Id: I5750db0504cb69ead52f9f44bf583e693bffbb7e

Added support for external frame buffers to libvpx's VP9 decoder.
If the external frame buffer functions are set then libvpx will
call the get function whenever it needs a new frame buffer to
decode a frame into. And it will call the release function
whenever there are no more references to that buffer.

Change-Id: Id2934d005f606af6e052fb6db0d5b7c02f567522

A future CL will add external frame buffers
differently.

Squash commit of four revert commits:
Revert "Increase required number of external frame buffers"

This reverts commit 9e41d569.

Revert "Add external constants."

This reverts commit bbf53047.

Revert "Add frame buffer lru cache."

This reverts commit fbada948.

Conflicts:
	vpxdec.c

Change-Id: I76fe42419923a6ea6c75d9997cbbf941d73d3005

Revert "Add support to pass in external frame buffers."

This reverts commit 10f89169.

Conflicts:
	test/external_frame_buffer_test.cc
	vp9/common/vp9_alloccommon.c
	vp9/common/vp9_reconinter.c
	vp9/decoder/vp9_decodeframe.c
	vp9/encoder/vp9_onyx_if.c
	vp9/vp9_dx_iface.c
	vpx/vpx_decoder.h
	vpx/vpx_external_frame_buffer.h
	vpx_scale/generic/yv12config.c
	vpxdec.c

Change-Id: I7434cf590f1c852b38569980e4247fad0d939c2e

VP9 decoder can now use frame buffers passed in by the application.

Change-Id: I599527ec85c577f3f5552831d79a693884fafb73

This patch adds support for building shared libraries when configured
with the --enable-shared switch.

Building DLLs would require more invasive changes to the sample
utilities than I want to make in this patch, since on Windows you can't
use the address of an imported symbol in a static initializer. The best
way to work around this is proably to build the codec interface mapping
table with an init() function, but dll support is of questionable value
anyway, since most windows users will probably use a media framework
lib like webmdshow, which links this library in staticly.

Change-Id: Iafb48900549b0c6b67f4a05d3b790b2643d026f4