Implemented parallel loopfiltering, which uses existing tile-
decoding threads. Each thread works on one row, and when that row
is loopfiltered, it moves to next unattended row. To ensure the
correct filtering order, threads are synchronized and one
superblock is filtered only if the superblocks it depends on are
filtered already.

To reduce synchronization overhead and speed up the decoder, we use
nsync > 1 for high resolution.

Performance tests:
1. on desktop:
8-tile 4k video using 8 threads, speedup: 70% - 80%
4-tile HD video using 4 threads, speedup: ~35%
2. on mobile device(Nexus 7):
4-tile 1080p video using 4 threads, speedup: 18% - 25%
4-tile 1080p video using 2 threads, speedup: 10% - 15%

Change-Id: If54b4a11960dd706c22d5ad145ad94156031f36a

When showing a previously decoded frame, i.e. when
show_existing_frame=1, the update of the
last_show_frame flag must be disabled.

This is to ensure that the last_show_frame flag
reflects the state of the flag for the immediately
previously decoded frame rather then the value that
was forced to ensure that a previously decoded frame
would be displayed.

This patch also adds a test vector to verify that the
display_existing_frame flag works as expected. Code
for generating the test vector can be found in this
patch:
https://gerrit.chromium.org/gerrit/#/c/68581/

(Bug originally reported by Alexander Voronov
<ru.xalba@gmail.com>).

Change-Id: I731d288fba02088959f7fcc87707137fffc6acf5

We don't use different filter kernels for x and y, it is always one kernel
for both directions.

Change-Id: Iefcbb02ec74bf46ea20d9dca672a3efd5d631517

Corresponding renames:
  subpel_kernel              => interp_kernel
  vp9_get_filter_kernel()    => vp9_get_interp_kernel()
  pred_filter_type           => pred_interp_filter
  adaptive_pred_filter_type  => adaptive_pred_interp_filter
  mcomp_filter_type          => interp_filter
  read_interp_filter_type()  => read_interp_filter()
  write_interp_filter_type() => write_interp_filter()
  fix_mcomp_filter_type()    => fix_interp_filter()

Change-Id: I1fa61fa1dc81ebbf043457c3ee2d8d4515bee6d3

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

Change-Id: I0e6aa00f220280e22d30d098545265835d0c1079

The change prevent a decoder crash for invalid stream with negative
size.

Change-Id: I7411765f3524c783058fa3d436549be4e75d8969

Encoder's boarder is still 160, while decoder's boarder will be 32.
With on demand and separate boarder buffer for boarder extension.
The decoder's boarder does not need to to 160 anymore.

Change-Id: I93d5aaff15a33a2213e9761eaa37c5f2870747db

When showing a previously decoded frame, we need to
explicitly set the show_frame flag.

For the current frame being decoded this flag is
explicitly set in the frame header.

This should fix WebM Issue 696:
http://code.google.com/p/webm/issues/detail?id=696

Change-Id: I5751a809813f88d2ca6f62c47c3878475ff9ba8d

This commit removes the use of best_mv in the decoding process. This
variable can be replaced with nearest_mv. It saves a few cycles on
assigning the values for best_mv.

Change-Id: Ic183f9c1fb615c54efd7e6ccfedcf09d493435e4

Change-Id: I5db2e5a6c36e6c503dea2e07d9d2e0daf4ac9d89

Adding RefBuffer to simplify reference buffer management. The struct has a
pointer to image data and scale factors relative to the current frame.

Change-Id: If38eb1491ff687cc11428aee339f3e052e2c5d9e

Change-Id: I50c009ff8108bda1c57427f23d63a79c04f7e776

Moving all code from that files to vp9_mvref_common.{h, c}.

Change-Id: Ibc4afcb8cea6847166ff411130e93611ebe63b20

Moving back to scale_factors struct. We don't need anymore x_offset_q4 and
y_offset_q4 because both values are calculated locally inside vp9_scale_mv
function.

Change-Id: I78a2122ba253c428a14558bda0e78ece738d2b5b

Subtracting the pointers promoted to a signed type.

Change-Id: Ied0e822a1756ed7b2f514efafcb6dce4efb9b9d6

Guard against incorrect size values moving *data past data_end.

Check read length against the difference of the buffers.

Change-Id: Ie0b54e2db517fd41a0f3ceb23402ee44839a4739

The definition fell out of sync in
I7d2fda72de5fc27e86c6589543b41fa044681dbf

Change-Id: I3ce3f6ba96bb121f51efaa08f64a69ad9f731a9e

Change-Id: Id677df4d3dbbed6fdf7319ca6464f19cf32c8176

Moving vp9_norm probability table from vp9_entropy.c to vp9_prob.c

Change-Id: Ie757b73860c6f43130790c332b292e2a1a81b788

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

Change-Id: I599527ec85c577f3f5552831d79a693884fafb73

set_offsets() is a right place to configure all mi-related pointers.

Change-Id: I7d2fda72de5fc27e86c6589543b41fa044681dbf

string literal to int within an assert

Change-Id: I0c889256b67a078e6e2a79577f0b7ae084243258

reorder the tiles based on size and their presumed complexity. this
minimizes the cases where the main thread is waiting on a worker to
complete.

Change-Id: Ie80642c6a1d64ece884f41683d23a3708ab38e0c

Replacing if-else with switch statement, reordering function arguments.

Change-Id: I4825d2ef311ba8999b6d4ceb0eef003587a13434

Renames:
  vp9_get_pred_context_mbskip => vp9_get_skip_context
  vp9_get_pred_prob_mbskip    => vp9_get_skip_prob

Change-Id: I2af499848ef73f3f5cd8cdb27852d0bcdfe31d09

the border now. Next commit will totally remove the border.

Change-Id: Ic1e1ca9cc34f81c688715b3948689b47df63a151

Change-Id: I83ffed2b1878a35ac35f07f9ee74309adc9c7b11

Change-Id: Ib4e215a80f00e342d857a54a4ca1b2dc82b6db1d

Change-Id: Ia6d6f4dfb1fd1ec0f8ba53796b59a802e9d7881d

Renames:
  vp9_get_pred_context_comp_inter_inter => vp9_get_reference_mode_context
  vp9_get_pred_prob_comp_inter_inter    => vp9_get_reference_mode_prob

Change-Id: I3bbb69481e6b0c848028667c9269f567f293d3bd

Change-Id: Ic3bb862e93aedf6a489a33ea6f7e5097d96855ee

Also adding BAND_COEFF_CONTEXTS macro to simplify for loop logic.

Change-Id: I12a78a49cf1addf81e6b3fe2a3736ec2b79bd79e

Renaming:
 vp9_get_pred_context_intra_inter => vp9_get_intra_inter_context
 vp9_get_pred_prob_intra_inter    => vp9_get_intra_inter_prob

Change-Id: I2c1affea2e84f4e616137c6df82adb11c7845781

NUM_YV12_BUFFERS        => FRAME_BUFFERS
ALLOWED_REFS_PER_FRAME  => REFS_PER_FRAME
NUM_REF_FRAMES_LOG2     => REF_FRAMES_LOG2
NUM_REF_FRAMES          => REF_FRAMES
NUM_FRAME_CONTEXTS_LOG2 => FRAME_CONTEXTS_LOG2
NUM_FRAME_CONTEXTS      => FRAME_CONTEXTS

Change-Id: I4e1ada08f25d8fa30fdf03aebe1b1c9df0f87e63

- Disable mode info update in case where current frame is coded
  as "show existing frame".
- Should fix issue 676.

Change-Id: Ibee681850eb307f982da6528d3e31cb94f881c08

Using consistent names (block_idx => block, dqcoeff_ptr => dqcoeff,
pt => ctx), inlining get_tx_eob() call.

Change-Id: I05208e57df81bbb8f25b8274684a48192e9de464

The old code would start in a mixed state, where all the reference
frames were pointing to frame buffer 0, but the reference counts
were 0. This is why we needed special code for the first frame.

Change-Id: I734961012917654ff8c0c8b317aac00ab75ded1a

In the decoder we don't need to save eobs, we can pass eob as an argument.
That's why removing eob arrays from VP9Decompressor and TileWorkerData,
and moving eob pointer from macroblockd_plane to macroblock_plane.

Change-Id: I8eb919acc837acfb3abdd8319af63d1bbca8217a

Renaming constants for consistency:
  DCT_VAL_CATEGORY1 => CATEGORY1_TOKEN
  DCT_VAL_CATEGORY2 => CATEGORY2_TOKEN
  DCT_VAL_CATEGORY3 => CATEGORY3_TOKEN
  DCT_VAL_CATEGORY4 => CATEGORY4_TOKEN
  DCT_VAL_CATEGORY5 => CATEGORY5_TOKEN
  DCT_VAL_CATEGORY6 => CATEGORY6_TOKEN
  DCT_EOB_TOKEN     => EOB_TOKEN
  DCT_EOB_MODEL_TOKEN => EOB_MODEL_TOKEN
  MAX_ENTROPY_TOKENS => ENTROPY_TOKENS

Moving constants:
  INTER_MODE_CONTEXTS from vp9_entropy.h to vp9_blockd.h.
  EOSB_TOKEN from vp9_entropy.h to vp9_tokenize.h

Change-Id: I5fcbf081318e1d365792b6d290a930c6cb0f3fc2