Setting chrome as the default browser is now fixed on Windows 10

chrome/browser/custom_handlers/protocol_handler_registry_unittest.cc

 // Copyright (c) 2012 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 "chrome/browser/custom_handlers/protocol_handler_registry.h"
 
 #include <set>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 216 matching lines @@
   ~FakeProtocolClientWorker() override {}
 
   ShellIntegration::DefaultWebClientState CheckIsDefault() override {
     if (force_failure_) {
       return ShellIntegration::NOT_DEFAULT;
     } else {
       return ShellIntegration::IS_DEFAULT;
     }
   }
 
-  bool SetAsDefault(bool interactive_permitted) override { return true; }
+  void SetAsDefault(bool interactive_permitted) override {
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&FakeProtocolClientWorker::CompleteSetAsDefault, this,
+                   true));
+  }
 
  private:
   bool force_failure_;
 };
 
 ProtocolHandlerRegistry::DefaultClientObserver*
     FakeDelegate::CreateShellObserver(ProtocolHandlerRegistry* registry) {
   return new FakeClientObserver(registry, this);
 }
 
@@ skipping 874 matching lines @@
   // added to pref.
   ASSERT_EQ(InPrefIgnoredHandlerCount(), 2);
   ASSERT_EQ(InMemoryIgnoredHandlerCount(), 4);
 
   registry()->RemoveIgnoredHandler(p2u1);
 
   // p2u1 installed by user and policy, so it is removed from pref alone.
   ASSERT_EQ(InPrefIgnoredHandlerCount(), 1);
   ASSERT_EQ(InMemoryIgnoredHandlerCount(), 4);
 }