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

chrome/browser/external_protocol/external_protocol_handler_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/external_protocol/external_protocol_handler.h"
 
 #include "base/message_loop/message_loop.h"
 #include "content/public/test/test_browser_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using content::BrowserThread;
 
 class FakeExternalProtocolHandlerWorker
     : public ShellIntegration::DefaultProtocolClientWorker {
  public:
   FakeExternalProtocolHandlerWorker(
       ShellIntegration::DefaultWebClientObserver* observer,
       const std::string& protocol,
       ShellIntegration::DefaultWebClientState os_state)
       : ShellIntegration::DefaultProtocolClientWorker(observer, protocol),
         os_state_(os_state) {}
 
  private:
   ~FakeExternalProtocolHandlerWorker() override {}
 
-  ShellIntegration::DefaultWebClientState CheckIsDefault() override {
-    return os_state_;
+  void CheckIsDefault() override {
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&FakeExternalProtocolHandlerWorker::OnCheckIsDefaultComplete,
+                   this, os_state_));
   }
 
-  bool SetAsDefault(bool interactive_permitted) override { return true; }
+  void SetAsDefault(bool interactive_permitted) override {
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(
+            &FakeExternalProtocolHandlerWorker::OnSetAsDefaultAttemptComplete,
+            this, AttemptResult::SUCCESS));
+  }
 
   ShellIntegration::DefaultWebClientState os_state_;
 };
 
 class FakeExternalProtocolHandlerDelegate
     : public ExternalProtocolHandler::Delegate {
  public:
   FakeExternalProtocolHandlerDelegate()
       : block_state_(ExternalProtocolHandler::BLOCK),
         os_state_(ShellIntegration::UNKNOWN_DEFAULT),
@@ skipping 144 matching lines @@
   DoTest(ExternalProtocolHandler::UNKNOWN,
          ShellIntegration::NOT_DEFAULT,
          true, false, false);
 }
 
 TEST_F(ExternalProtocolHandlerTest, TestLaunchSchemeUnknownChromeUnknown) {
   DoTest(ExternalProtocolHandler::UNKNOWN,
          ShellIntegration::UNKNOWN_DEFAULT,
          true, false, false);
 }