Allow fallback from https to http for component update checks.

components/component_updater/configurator_impl.cc

 // 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.
 
 #include "components/component_updater/configurator_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 64 matching lines @@
       }
     }
   }
   return std::string();
 }
 
 }  // namespace
 
 ConfiguratorImpl::ConfiguratorImpl(
     const base::CommandLine* cmdline,
-    net::URLRequestContextGetter* url_request_getter)
+    net::URLRequestContextGetter* url_request_getter,
+    bool require_encryption)
     : url_request_getter_(url_request_getter),
       fast_update_(false),
       pings_enabled_(false),
       deltas_enabled_(false),
-      background_downloads_enabled_(false) {
+      background_downloads_enabled_(false),
+      require_encryption_(require_encryption) {
   // Parse comma-delimited debug flags.
   std::vector<std::string> switch_values = base::SplitString(
       cmdline->GetSwitchValueASCII(switches::kComponentUpdater), ",",
       base::KEEP_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
   fast_update_ = HasSwitchValue(switch_values, kSwitchFastUpdate);
   pings_enabled_ = !HasSwitchValue(switch_values, kSwitchDisablePings);
   deltas_enabled_ = !HasSwitchValue(switch_values, kSwitchDisableDeltaUpdates);
 
 #if defined(OS_WIN)
   background_downloads_enabled_ =
@@ skipping 32 matching lines @@
 }
 
 int ConfiguratorImpl::UpdateDelay() const {
   return fast_update_ ? 10 : (15 * kDelayOneMinute);
 }
 
 std::vector<GURL> ConfiguratorImpl::UpdateUrl() const {
   std::vector<GURL> urls;
   if (url_source_override_.is_valid()) {
     urls.push_back(GURL(url_source_override_));
-  } else {
-    urls.push_back(GURL(kUpdaterDefaultUrl));
+    return urls;
   }
+
+  urls.push_back(GURL(kUpdaterDefaultUrl));
+  urls.push_back(GURL(kUpdaterFallbackUrl));
+  if (require_encryption_) {
+    urls.erase(std::remove_if(urls.begin(), urls.end(),
+                              [](const GURL& url) {
+                                return !url.SchemeIsCryptographic();
+                              }),
+               urls.end());
+  }
+
   return urls;
 }
 
 std::vector<GURL> ConfiguratorImpl::PingUrl() const {
   return pings_enabled_ ? UpdateUrl() : std::vector<GURL>();
 }
 
 base::Version ConfiguratorImpl::GetBrowserVersion() const {
   return base::Version(version_info::GetVersionNumber());
 }
@@ skipping 20 matching lines @@
 
 bool ConfiguratorImpl::UseBackgroundDownloader() const {
   return background_downloads_enabled_;
 }
 
 bool ConfiguratorImpl::UseCupSigning() const {
   return true;
 }
 
 }  // namespace component_updater