Run cpplint as part of our CI build

This will help ensure a consistent C++ coding style.
Fix cpplint errors in browser_client.cc
Fix cpplint errors in browser_context.cc
Fix cpplint errors in browser_main_parts.cc
Don't require all files to have a copyright/license header

The LICENSE file at the root of the repository is enough.
Fix cpplint errors in default_web_contents_delegate.cc
Fix cpplint errors in devtools_ui.cc
Fix cpplint errors in inspectable_web_contents.cc
Fix cpplint errors in inspectable_web_contents_impl.cc
Fix cpplint errors in network_delegate.cc
Fix cpplint errors in url_request_context_getter.cc
Fix cpplint errors in web_ui_controller_factory.cc
Fix cpplint errors in browser_client.h
Fix cpplint errors in browser_context.h
Build before running cpplint

Let's make sure things build before we check coding style. If it doesn't
even build, who cares about the style?
Fix typos
Fix cpplint errors in browser_main_parts.h
Fix cpplint errors in default_web_contents_delegate.h
Fix all remaining readability/namespace errors
Fix cpplint errors in inspectable_web_contents.h