The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8

commit f509215b691cd8d082cc4f5e9d0b3ef133e34eb8
Author: Takumi Fujimoto <takumif@chromium.org>
Date: Tue Nov 14 15:35:41 2017

[Media Router] Add presentation_id attribute to MediaRoute to enable MRP lookup

MediaRouterMojoImpl::JoinRoute() requires that we find the MediaRouteProvider associated with a presentation ID.
By associating each MediaRoute with a presentation ID, we can look up the associated MRP.
The change to add presentation ID to MediaRoute on the component extension side has landed as cl/173960916.

Bug:  779155 ,  761493 
Change-Id: I4bf7d6fb3a832ef4720bfc1952198fd2036350b2
Reviewed-on: https://chromium-review.googlesource.com/757796
Reviewed-by: Derek Cheng <imcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516307}
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/browser/media/router/mojo/media_router_desktop.cc
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/browser/media/router/mojo/media_router_desktop.h
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/browser/media/router/mojo/media_router_mojo_impl.cc
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/browser/media/router/mojo/media_router_mojo_impl.h
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/browser/media/router/mojo/media_router_mojo_impl_unittest.cc
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/browser/media/router/mojo/media_router_mojo_test.cc
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/common/media_router/media_route.h
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/common/media_router/mojo/media_router.mojom
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/common/media_router/mojo/media_router_struct_traits.cc
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/common/media_router/mojo/media_router_struct_traits.h
[modify] https://crrev.com/f509215b691cd8d082cc4f5e9d0b3ef133e34eb8/chrome/renderer/resources/extensions/media_router_bindings.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bead1184f0512718d766fc89d33cea6ec1ca0fd1

commit bead1184f0512718d766fc89d33cea6ec1ca0fd1
Author: Takumi Fujimoto <takumif@chromium.org>
Date: Tue Nov 14 23:11:47 2017

[Media Router] Update safeguards in media_router_bindings

Adding a default value for presentation ID in routeToMojo_().
Also removing safeguards that are no longer necessary.

Bug:  779155 
Change-Id: I4d39e3dcc1d5495d02c794b693f2f18824bcff4d
Reviewed-on: https://chromium-review.googlesource.com/769570
Reviewed-by: Derek Cheng <imcheng@chromium.org>
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516489}
[modify] https://crrev.com/bead1184f0512718d766fc89d33cea6ec1ca0fd1/chrome/renderer/resources/extensions/media_router_bindings.js