Roll src/third_party/ffmpeg/ 5659adb8f..ddbe19a87 (2 commits)

https://chromium.googlesource.com/chromium/third_party/ffmpeg.git/+log/5659adb8fc6f..ddbe19a87228

$ git log 5659adb8f..ddbe19a87 --date=short --no-merges --format='%ad %ae %s'
2018-08-14 modmaker avformat/mov: Allow saio/saiz in clear content.
2018-08-13 modmaker avutil/encryption_info: Fix size calculation.

Created with:
  roll-dep src/third_party/ffmpeg

Bug: 873432, 873693
Change-Id: I2d15352a47c30de4bf75df064388a8d3803930c2
Tbr: tguilbert
Reviewed-on: https://chromium-review.googlesource.com/1175147Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583108}

DEPS

@@ -617,7 +617,7 @@ deps = {
   },
 
   'src/third_party/ffmpeg':
-    Var('chromium_git') + '/chromium/third_party/ffmpeg.git' + '@' + '5659adb8fc6f7228699d4cf45d95f73624d5aeb7',
+    Var('chromium_git') + '/chromium/third_party/ffmpeg.git' + '@' + 'ddbe19a87228d61d131fe3b1876cd68bb4cbc3be',
 
   'src/third_party/flac':
     Var('chromium_git') + '/chromium/deps/flac.git' + '@' + 'af862024c8c8fa0ae07ced05e89013d881b00596',