GN: Have //content/renderer depend on //mojo/common.
GN: Have //content/renderer depend on //mojo/common.

render_thread_impl.cc depends on common_type_converters.h as well as
url_type_converters.h, so it should depend on the higher level :common
group target.

This resolves an error in `gn check out/Default //content/renderer:*`.

Review URL: https://codereview.chromium.org/1571413002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#368976}

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