[Background Fetch] Finish integration of backgroundFetch

permission with devtools.

This was suggested a previous review:
https://chromium-review.googlesource.com/c/chromium/src/+/1233714/18/content/browser/devtools/protocol/browser_handler.cc#140

Bug: 886896
Change-Id: I41e850811da4c8d11f091b2fb0b49320af6cd0e4
Reviewed-on: https://chromium-review.googlesource.com/c/1278926Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Mugdha Lakhani <nator@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599271}

content/browser/devtools/protocol/browser_handler.cc

@@ -138,6 +138,8 @@ Response FromProtocolPermissionType(
     *out_type = PermissionType::CLIPBOARD_WRITE;
   } else if (type == protocol::Browser::PermissionTypeEnum::PaymentHandler) {
     *out_type = PermissionType::PAYMENT_HANDLER;
+  } else if (type == protocol::Browser::PermissionTypeEnum::BackgroundFetch) {
+    *out_type = PermissionType::BACKGROUND_FETCH;
   } else {
     return Response::InvalidParams("Unknown permission type: " + type);
   }

third_party/blink/renderer/core/inspector/browser_protocol.pdl

@@ -490,6 +490,7 @@ domain Browser
       accessibilityEvents
       audioCapture
       backgroundSync
+      backgroundFetch
       clipboardRead
       clipboardWrite
       durableStorage