Implement updateViaCache flag and no-cache by default for main service worker scripts

content/browser/service_worker/service_worker_database.proto

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package content;
 
 message ServiceWorkerOriginTrialFeature {
   required string name = 1;
   repeated string tokens = 2;
 }
 
 message ServiceWorkerOriginTrialInfo {
   repeated ServiceWorkerOriginTrialFeature features = 1;
 }
 
 message ServiceWorkerNavigationPreloadState {
   required bool enabled = 1;
   optional string header = 2;
 }
 
 message ServiceWorkerRegistrationData {
+  enum ServiceWorkerUpdateViaCacheType {
+    UNKNOWN = 0;

[nhiroki, 2017/08/04 09:24:50]

I wonder if we don't have to have UNKNOWN type because we shouldn't write a
registration data to the DB if its cache type is "UNKNOWN".

[yuryu, 2017/08/17 07:36:35]

Done.

+    IMPORTS = 1;
+    ALL = 2;
+    NONE = 3;
+  }
+
   required int64 registration_id = 1;
   required string scope_url = 2;
   required string script_url = 3;
 
   // Versions are first stored once they successfully install and become the
   // waiting version. Then they are updated when they transition to the active
   // version.
   required int64 version_id = 4;
 
   required bool is_active = 5;
@@ skipping 11 matching lines @@
   // |origin_trial_tokens| is not set. In this case, we have to start the
   // Service Worker and load the main script resource in ServiceWorkerStorage
   // to check the HTTP header.
   optional ServiceWorkerOriginTrialInfo origin_trial_tokens = 11;
 
   optional ServiceWorkerNavigationPreloadState navigation_preload_state = 12;
 
   // The set of features that the worker used up until the time installation
   // completed. The values must be from blink::UseCounter::Feature enum.
   repeated uint32 used_features = 13;
+
+  optional ServiceWorkerUpdateViaCacheType update_via_cache = 14
+      [default = IMPORTS];
 }
 
 message ServiceWorkerResourceRecord {
   required int64 resource_id = 1;
   required string url = 2;
   optional uint64 size_bytes = 3;
 }