Allow fallback from https to http for component update checks.

components/update_client/update_client.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_
 #define COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
@@ skipping 125 matching lines @@
 
 namespace update_client {
 
 class Configurator;
 struct CrxUpdateItem;
 
 enum Error {
   ERROR_UPDATE_INVALID_ARGUMENT = -1,
   ERROR_UPDATE_IN_PROGRESS = 1,
   ERROR_UPDATE_CANCELED = 2,
+  ERROR_UPDATE_RETRY_LATER = 3,
 };
 
 // Defines an interface for a generic CRX installer.
 class CrxInstaller : public base::RefCountedThreadSafe<CrxInstaller> {
  public:
   // Called on the main thread when there was a problem unpacking or
   // verifying the CRX. |error| is a non-zero value which is only meaningful
   // to the caller.
   virtual void OnUpdateError(int error) = 0;
 
@@ skipping 34 matching lines @@
   scoped_refptr<CrxInstaller> installer;
 
   // The current version if the CRX is updated. Otherwise, "0" or "0.0" if
   // the CRX is installed.
   Version version;
 
   std::string fingerprint;  // Optional.
   std::string name;         // Optional.
 
   // Specifies that the CRX can be background-downloaded in some cases.
-  // The default for this value is |true| and the value can be overriden at
-  // the registration time. This is a temporary change until the issue
-  // crbug/340448 is resolved.
-  bool allow_background_download;
+  // The default for this value is |true|.
+  bool allows_background_download;
+
+  // Specifies that the update checks and pings associated with this component
+  // require confidentiality. The default for this value is |true|. As a side
+  // note, the confidentiality of the downloads is enforced by the server,
+  // which only returns secure download URLs in this case.
+  bool requires_network_encryption;
 };
 
 // All methods are safe to call only from the browser's main thread. Once an
 // instance of this class is created, the reference to it must be released
 // only after the thread pools of the browser process have been destroyed and
 // the browser process has gone single-threaded.
 class UpdateClient : public base::RefCounted<UpdateClient> {
  public:
   using CrxDataCallback =
       base::Callback<void(const std::vector<std::string>& ids,
@@ skipping 106 matching lines @@
   virtual ~UpdateClient() {}
 };
 
 // Creates an instance of the update client.
 scoped_refptr<UpdateClient> UpdateClientFactory(
     const scoped_refptr<Configurator>& config);
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_