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

chrome/browser/ui/startup/startup_browser_creator.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/ui/startup/startup_browser_creator.h"
 
 #include <algorithm>   // For max().
 #include <set>
 
 #include "apps/app_load_service.h"
@@ skipping 88 matching lines @@
 #include "chrome/browser/printing/cloud_print/cloud_print_proxy_service.h"
 #include "chrome/browser/printing/cloud_print/cloud_print_proxy_service_factory.h"
 #include "chrome/browser/printing/print_dialog_cloud.h"
 #endif
 
 using content::BrowserThread;
 using content::ChildProcessSecurityPolicy;
 
 namespace {
 
+const wchar_t kSetDefaultBrowserHelpUrl[] =
+    L"https://support.google.com/chrome?p=default_browser";
+
+// Not thread-safe. Always use or modify this callback on the UI thread.
+base::Closure* g_default_browser_callback = nullptr;
+
 // Keeps track on which profiles have been launched.
 class ProfileLaunchObserver : public content::NotificationObserver {
  public:
   ProfileLaunchObserver()
       : profile_to_activate_(NULL),
         activated_profile_(false) {
     registrar_.Add(this, chrome::NOTIFICATION_PROFILE_DESTROYED,
                    content::NotificationService::AllSources());
     registrar_.Add(this, chrome::NOTIFICATION_BROWSER_WINDOW_READY,
                    content::NotificationService::AllSources());
@@ skipping 320 matching lines @@
 // static
 void StartupBrowserCreator::RegisterLocalStatePrefs(
     PrefRegistrySimple* registry) {
 #if defined(OS_WIN)
   registry->RegisterStringPref(prefs::kLastWelcomedOSVersion, std::string());
   registry->RegisterBooleanPref(prefs::kWelcomePageOnOSUpgradeEnabled, true);
 #endif
 }
 
 // static
+bool StartupBrowserCreator::SetDefaultBrowserCallback(
+    const base::Closure& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (!g_default_browser_callback) {
+    g_default_browser_callback = new base::Closure(callback);

[Peter Kasting, 2015/09/25 20:52:27]

Nit: I might add a comment here on why this can't leak.

[Patrick Monette, 2015/09/28 23:46:38]

Done.

+    return true;
+  }
+  return false;
+}
+
+// static
+void StartupBrowserCreator::ClearDefaultBrowserCallback() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (g_default_browser_callback) {

[grt (UTC plus 2), 2015/09/28 14:31:04]

delete null is well-defined in C++, so you could remove this if() and
unconditionally do the delete and assignment. otherwise, one can imagine that
this code (which is only expected to be called when g_default_browser_callback
isn't null) will actually do two null checks on every call.

[Patrick Monette, 2015/09/28 23:46:38]

Done.

+    delete g_default_browser_callback;
+    g_default_browser_callback = nullptr;
+  }
+}
+
+// static
+const wchar_t* StartupBrowserCreator::GetDefaultBrowserUrl() {
+  return kSetDefaultBrowserHelpUrl;
+}
+
+// static
 std::vector<GURL> StartupBrowserCreator::GetURLsFromCommandLine(
     const base::CommandLine& command_line,
     const base::FilePath& cur_dir,
     Profile* profile) {
   std::vector<GURL> urls;
 
   const base::CommandLine::StringVector& params = command_line.GetArgs();
   for (size_t i = 0; i < params.size(); ++i) {
     base::FilePath param = base::FilePath(params[i]);
     // Handle Vista way of searching - "? <search-term>"
@@ skipping 45 matching lines @@
 }
 
 // static
 bool StartupBrowserCreator::ProcessCmdLineImpl(
     const base::CommandLine& command_line,
     const base::FilePath& cur_dir,
     bool process_startup,
     Profile* last_used_profile,
     const Profiles& last_opened_profiles,
     StartupBrowserCreator* browser_creator) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
   TRACE_EVENT0("startup", "StartupBrowserCreator::ProcessCmdLineImpl");
 
   DCHECK(last_used_profile);
   if (process_startup) {
     if (command_line.HasSwitch(switches::kDisablePromptOnRepost))
       content::NavigationController::DisablePromptOnRepost();
   }
 
   bool silent_launch = false;
 
@@ skipping 119 matching lines @@
     // Return early here since we don't want to open a browser window.
     // The exception is when there are no browser windows, since we don't want
     // chrome to shut down.
     // TODO(jackhou): Do this properly once keep-alive is handled by the
     // background page of apps. Tracked at http://crbug.com/175381
     if (chrome::GetTotalBrowserCountForProfile(last_used_profile) != 0)
       return true;
   }
 
 #if defined(OS_WIN)
+  // Intercept a specific url when setting the default browser asynchronously.
+  // This only happens on Windows 10+.
+  if (g_default_browser_callback) {
+    base::CommandLine::StringType default_browser_url_(
+        kSetDefaultBrowserHelpUrl);
+    for (const auto& arg : command_line.GetArgs()) {
+      if (arg == default_browser_url_) {
+        g_default_browser_callback->Run();
+        return true;
+      }
+    }
+  }
+
   // Log whether this process was a result of an action in the Windows Jumplist.
   if (command_line.HasSwitch(switches::kWinJumplistAction)) {
     jumplist::LogJumplistActionFromSwitchValue(
         command_line.GetSwitchValueASCII(switches::kWinJumplistAction));
   }
-#endif
+#endif  // defined(OS_WIN)
 
   chrome::startup::IsProcessStartup is_process_startup = process_startup ?
       chrome::startup::IS_PROCESS_STARTUP :
       chrome::startup::IS_NOT_PROCESS_STARTUP;
   chrome::startup::IsFirstRun is_first_run = first_run::IsChromeFirstRun() ?
       chrome::startup::IS_FIRST_RUN : chrome::startup::IS_NOT_FIRST_RUN;
   // |last_opened_profiles| will be empty in the following circumstances:
   // - This is the first launch. |last_used_profile| is the initial profile.
   // - The user exited the browser by closing all windows for all
   // profiles. |last_used_profile| is the profile which owned the last open
@@ skipping 173 matching lines @@
   // If we are showing the app list then chrome isn't shown so load the app
   // list's profile rather than chrome's.
   if (command_line.HasSwitch(switches::kShowAppList)) {
     return AppListService::Get(chrome::HOST_DESKTOP_TYPE_NATIVE)->
         GetProfilePath(user_data_dir);
   }
 
   return g_browser_process->profile_manager()->GetLastUsedProfileDir(
       user_data_dir);
 }