Replace src/ios copy with DEPS mirror.

DEPS

 # This file contains dependencies for WebRTC.
 
 vars = {
   'chromium_git': 'https://chromium.googlesource.com',
   'chromium_revision': 'c755988946c0b539cc61cc55d38ae056e0356c27',
   'boringssl_git': 'https://boringssl.googlesource.com',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
   'swarming_revision': 'ebc8dab6f8b8d79ec221c94de39a921145abd404',
@@ skipping 25 matching lines @@
 
 deps = {
   # TODO(kjellander): Move this to be Android-only once the libevent dependency
   # in base/third_party/libevent is solved.
   'src/base':
     Var('chromium_git') + '/chromium/src/base' + '@' + 'eacf0248426ad9032a9dd0c980eb1d9aa1a45f40',
   'src/build':
     Var('chromium_git') + '/chromium/src/build' + '@' + '6f17189f6eafdffbe6a5a646b85fe0f0440cd406',
   'src/buildtools':
     Var('chromium_git') + '/chromium/buildtools.git' + '@' + 'a7cc7a3e21a061975b33dcdcd81a9716ba614c3c',
+  'src/ios':

[kthelgason, 2017/01/26 14:45:34]

Shouldn't this be down in `deps_os`? No need to pull it in all the time right?

[kjellander_webrtc, 2017/01/26 15:11:10]

Yes it seems to work. I was afraid it wouldn't due to references in Chromium
that were processed on all platforms (since the dir is always there in Chromium
since it's not a DEPS entry). But deps_os works (proven by the other platform
trybots being green). Thanks for the suggestion.

+    Var('chromium_git') + '/chromium/src/ios' + '@' + '44a908d160175dd44c8a66c66d912066bcb364fd',
   'src/testing':
     Var('chromium_git') + '/chromium/src/testing' + '@' + 'b9561eff5941f4c762ee8a33c0b768b397f5f3c9',
   'src/testing/gtest':
     Var('chromium_git') + '/external/github.com/google/googletest.git' + '@' + '6f8a66431cb592dad629028a50b3dd418a408c87',
   'src/testing/gmock':
     Var('chromium_git') + '/external/googlemock.git' + '@' + '0421b6f358139f02e102c9c332ce19a33faf75be', # from svn revision 566
   'src/third_party':
     Var('chromium_git') + '/chromium/src/third_party' + '@' + 'c13a9b4abc5d99cd01cff12258a5d67fb890ae80',
   'src/third_party/boringssl/src':
    Var('boringssl_git') + '/boringssl.git' + '@' +  Var('boringssl_revision'),
@@ skipping 467 matching lines @@
   },
 ]
 
 recursedeps = [
   # buildtools provides clang_format, libc++, and libc++abi.
   'src/buildtools',
   # android_tools manages the NDK.
   'src/third_party/android_tools',
 ]