Adding third_party/openh264/src, build files and unittests

DEPS

 # This file is used to manage the dependencies of the Chromium src repo. It is
 # used by gclient to determine what version of each dependency to check out, and
 # where.
 #
 # For more information, please refer to the official documentation:
 #   https://sites.google.com/a/chromium.org/dev/developers/how-tos/get-the-code
 #
 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 #
@@ skipping 263 matching lines @@
 
   'src/third_party/py_trace_event/src':
     Var('chromium_git') + '/external/py_trace_event.git' + '@' + 'dd463ea9e2c430de2b9e53dea57a77b4c3ac9b30',
 
   'src/third_party/dom_distiller_js/dist':
     Var('chromium_git') + '/external/github.com/chromium/dom-distiller-dist.git' + '@' + '445b024cb55f367636e6da4a61796a2afecd6d3f',
 
   'src/third_party/catapult':
     Var('chromium_git') + '/external/github.com/catapult-project/catapult.git' + '@' +
     'e2c6869c72944a7a7a729c7ccc9fdc1f8f90de8e',
+
+  'src/third_party/openh264/src':
+    Var('chromium_git') + '/external/github.com/cisco/openh264' + '@' + 'b37cda248234162033e3e11b0335f3131cdfe488',
 }
 
 
 deps_os = {
   'win': {
     'src/chrome/tools/test/reference_build/chrome_win':
      Var('chromium_git') + '/chromium/reference_builds/chrome_win.git' + '@' + 'f8a3a845dfc845df6b14280f04f86a61959357ef',
 
     'src/third_party/cygwin':
      Var('chromium_git') + '/chromium/deps/cygwin.git' + '@' + 'c89e446b273697fadf3a10ff1007a97c0b7de6df',
@@ skipping 525 matching lines @@
     'pattern': '.',
     'action': [
         'python',
         'src/tools/check_git_config.py',
         '--running-as-hook',
     ],
   },
 ]