Hope it will save some time for you. If you see

AssertionError: Multiple codesigning identities for identity: iPhone Developer

and don’t know how to fix, when building webrtc, libyuv or any other libraries with Google’s depot tools, simplest fix you can do is just remove the assertion. You don’t need developer’s profile and binary singing for libraries. That’s obvious for you, but not obvious for the script. 🙂 In my case, I found the assertion in the /chromium/src/tools/gyp/pylib/gyp/xcode_emulation.py.

P.S. Found similar post on Stackoverflow.