Updating OpenH264 to v1.7.0

There is bug in AQ in v1.6.0 which causes very poor video quality in
WebRTC when packetization mode 0 is used. The issue is fixed in v1.7
(https://github.com/cisco/openh264/releases/tag/v1.7.0).

I modified MediaRecorderHandlerTest/EncodeVideoFrames test to make it
pass with new encoder. The test expects encoded frame sizes to be
equal or bigger than the hard coded thresholds. But due to changes in
RC the new encoder uses different QPs. As result there is difference
in frame sizes: the second frame produced by the new encoder is 1
byte smaller than the previous version produced. The test failed
because of that. I changed the threshold from 13 to 12 bytes to make
it work with the new version (it still works with previous version as
well).

Bug: webrtc:8070
Change-Id: I58f82be70b12f26bea306f7788d33db9aca47856
Reviewed-on: https://chromium-review.googlesource.com/674868Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Commit-Queue: Sergey Silkin <ssilkin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505104}

DEPS

@@ -307,7 +307,7 @@ deps = {
     Var('chromium_git') + '/catapult.git' + '@' + Var('catapult_revision'),
 
   'src/third_party/openh264/src':
-    Var('chromium_git') + '/external/github.com/cisco/openh264' + '@' + '0fd88df93c5dcaf858c57eb7892bd27763f0f0ac',
+    Var('chromium_git') + '/external/github.com/cisco/openh264' + '@' + 'a180c9d4d6f1a4830ca9eed9d159d54996bd63cb',
 
   'src/third_party/re2/src':
     Var('chromium_git') + '/external/github.com/google/re2.git' + '@' + 'ae9cb49a2e2ba95de4f0c6ec5a8afd039996d2c7',

content/renderer/media_recorder/media_recorder_handler_unittest.cc

@@ -258,7 +258,7 @@ TEST_P(MediaRecorderHandlerTest, EncodeVideoFrames) {
   Mock::VerifyAndClearExpectations(this);
 
   {
-    const size_t kEncodedSizeThreshold = 13;
+    const size_t kEncodedSizeThreshold = 12;
     base::RunLoop run_loop;
     base::Closure quit_closure = run_loop.QuitClosure();
     // The second time around writeData() is called a number of times to write