Adding third_party/openh264/src, build files and unittests

build/all.gyp

Index: build/all.gyp
diff --git a/build/all.gyp b/build/all.gyp
index ef9ad981e65e7b4f104fcc1419cc9ebacd4791f3..9145dc6056927d70c99071f12b13930af315abc4 100644
--- a/build/all.gyp
+++ b/build/all.gyp
@@ -30,7 +30,6 @@
         '../testing/gtest.gyp:*',
         '../third_party/icu/icu.gyp:*',
         '../third_party/libxml/libxml.gyp:*',
-        '../third_party/openh264/tests/openh264_unittests.gyp:*',
         '../third_party/sqlite/sqlite.gyp:*',
         '../third_party/zlib/zlib.gyp:*',
         '../ui/accessibility/accessibility.gyp:*',
@@ -289,6 +288,11 @@
             '../envoy/envoy.gyp:*',
           ],
         }],
+        ['build_openh264==1', {
+          'dependencies': [
+            '../third_party/openh264/openh264.gyp:*',
+          ],
+        }],
       ],
     }, # target_name: All
     {