The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1213d18447982bca833d6adb1a5e0a29c3713e62

commit 1213d18447982bca833d6adb1a5e0a29c3713e62
Author: Xiaohan Wang <xhwang@chromium.org>
Date: Thu Oct 12 19:47:26 2017

media: Run CDM service in utility process with CDM sandbox

- In cdm_manifest.json, register the CDM service to run with "cdm"
  sandbox type.
- The "cdm" sandbox type has different meanings on different platforms.
  * Linux: see bpf_cdm_policy_linux.cc
  * Mac: see cdm.sb
  * Windows: sandbox initialization is delayed; same as ppapi process.
- This is how CDM loading works on each platform:
  * On Linux, preload all registered CDMs in the zygote process, similar
    to how all registered pepper plugins are preloaded. This would allow
    access to the CDMs in the utility process (forked from the zygote).
  * On Mac, updates media_service.mojom to pass an interface to get a
    sandbox seatbelt extension token from the browser process. This
    token can be used to allow to read the CDM within the Mac sandbox.
    On the browser side, the mojom::SeatbeltExtensionTokenProvider is
    implemented by SeatbeltExtensionTokenProviderImpl to provide the
    token we call LoadCdm() in MediaInterfaceProxy. The token will only
    be created the first time we connect to the service.
  * On Windows, the sandbox initialization is delayed for the "cdm"
    sandbox type. After the CDM is loaded, the process will be sandboxed
    immediately. This is the same as how the CDM is loaded with ppapi
    sandbox today.
- Add EnsureSandboxed() on MojoMediaClient interface to ensure we
  initialize the sandbox on Windows.

BUG=510604, 764840 
TEST=Tested on Linux, Windows and Mac. All browser_tests passes.

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_site_isolation
Change-Id: I24260e435175bd57257fd377eec7226b1b782552
Reviewed-on: https://chromium-review.googlesource.com/667930
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508388}
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/content/browser/browser_main_loop.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/content/browser/frame_host/render_frame_host_impl.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/content/browser/media/media_interface_proxy.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/content/browser/zygote_host/zygote_communication_linux.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/content/utility/utility_main.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/content/utility/utility_service_factory.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/content/zygote/zygote_main_linux.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/DEPS
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/interfaces/BUILD.gn
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/interfaces/media_service.mojom
[add] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/interfaces/media_service_mac.mojom
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/services/BUILD.gn
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/services/cdm_manifest.json
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/services/media_service.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/services/media_service.h
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/services/media_service_unittest.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/services/mojo_media_client.cc
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/media/mojo/services/mojo_media_client.h
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/services/service_manager/sandbox/mac/BUILD.gn
[add] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/services/service_manager/sandbox/mac/cdm.sb
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/services/service_manager/sandbox/mac/sandbox_mac.h
[modify] https://crrev.com/1213d18447982bca833d6adb1a5e0a29c3713e62/services/service_manager/sandbox/mac/sandbox_mac.mm