Roll src/third_party/libvpx/source/libvpx/ 6a0e77155..83f17eeed (26 commits).

https://chromium.googlesource.com/webm/libvpx.git/+log/6a0e77155527..83f17eeede83

$ git log 6a0e77155..83f17eeed --date=short --no-merges --format='%ad %ae %s'
2016-04-20 marpan vp9: 1 pass vbr: Small fix on reset avg_intersize_gfint on scene cut.
2016-04-20 marpan vp9: 1 pass vbr: small adjustment to active_best factor for inter.
2016-04-19 marpan vp9: Adjust gf period for high average Q and overshoot.
2016-04-19 marpan vp8: Update on sum_diff_threshold.
2016-04-18 marpan vp9: 1 pass vbr: More even spacing for gf near key frame.
2016-04-15 marpan vp9: Adjustment to active_best_quality for inter_frame, 1 pass vbr.
2016-04-15 slavarnway VP9: inline vp9_get_intra_inter_context()
2016-03-03 martin Enable vpx_idct32x32_1024_add_neon for neon as well, not only for neon_asm
2016-04-14 johannkoenig Apply 'const' to data not pointer
2016-04-13 marpan vp9: Adjustment to scene-cut detection.
2016-04-13 yunqingwang Fix Visual Studio build warning
2016-04-13 jzern dct32x32_test: s/HAVE_NEON_ASM/HAVE_NEON/
2016-04-12 marpan vp9: Adjust threshold for scene-change detection.
2016-04-12 aconverse Increase active map test coverage from RT speeds 0-5 to 0-8.
2016-04-07 marpan vp9: Fix to active_best for GF/ARF in 1 pass vbr.
2016-03-03 martin configure: Detect aarch64 toolchains automatically
2016-03-03 martin configure: Add an arm64-linux-gcc target configuration
2016-04-11 aconverse pickmode: only cost the skip flag once per prediction block
2016-03-30 paulwilkins Adjustment to prediction decay.
2016-04-09 debargha Step towards making the 2-pass cq mode perceptual
(...)

R=johannkoenig@google.com

Review URL: https://codereview.chromium.org/1911413003

Cr-Commit-Position: refs/heads/master@{#389169}

diff --git a/DEPS b/DEPS
index fad7cee..6704fc6 100644
--- a/DEPS
+++ b/DEPS

@@ -186,7 +186,7 @@
     Var('chromium_git') + '/external/selenium/py.git' + '@' + '5fd78261a75fe08d27ca4835fb6c5ce4b42275bd',
 
   'src/third_party/libvpx/source/libvpx':
-   Var('chromium_git') + '/webm/libvpx.git' + '@' +  '6a0e7715552758f016d3a79838021528b6bf9bf2',
+   Var('chromium_git') + '/webm/libvpx.git' + '@' +  '83f17eeede83f138f34177121019798719d5be1c',
 
   'src/third_party/ffmpeg':
    Var('chromium_git') + '/chromium/third_party/ffmpeg.git' + '@' + 'beef68513861e11156899b1f763097c31808c418',