Reland: Web MIDI: use mojom::blink::PermissionService directly to ask permission

Changes from the first attempt:

- AwPermissionManager::RequestPermissions() was implemented for
  Android WebView in a separate CL.
- Workarounds to avoid touching NOTIMPLEMENTED() was removed

Original description follows:

SystemWebViewShellLayoutTest failed because of the same reason with
other modified tests in this CL. Tests are modified to pass, but now
it does not cover {sysex:true} case that needs
AwPermissionManager::RequestPermissions implementation.
It will be implemented in the next CL soon.

Original description follows:
Web MIDI asked permissions via public/web interfaces.
But now that PermissionService is available in Blink,
use the service to ask permissions.

This migration makes it possible to remove all MIDI
related public/web interfaces.

BUG=582328

Committed: https://crrev.com/15c1a1ffd1f4c620b89191209dc76ef5557dd8fc
Cr-Commit-Position: refs/heads/master@{#404136}

TEST=${OUT}/bin/run_system_webview_shell_layout_test_apk # with a built SystemWebViewGoogle.apk
TEST=git cl try

Review-Url: https://codereview.chromium.org/2116763002
Cr-Commit-Position: refs/heads/master@{#408621}
32 files changed