We have a file in extensions/ [1] that depends on Media Router mojo definitions
from chrome/browser/. To remove this dependency from extensions/ to
chrome/browser/, this CL moves that file to chrome/renderer/, and Media Router
mojo interfaces to chrome/common/media_router/mojo/. Media Router typemaps and
related C++ structs are also moved to chrome/common/media_router/.

[1] extensions/renderer/resources/media_router_bindings.js

BUG=704958

Review-Url: https://codereview.chromium.org/2771413003
Cr-Commit-Position: refs/heads/master@{#465734}