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

chrome/browser/shell_integration_win.cc

Index: chrome/browser/shell_integration_win.cc
diff --git a/chrome/browser/shell_integration_win.cc b/chrome/browser/shell_integration_win.cc
index 07f7b4b9f8e465faaad7240654e82ebedbb91644..0ff9d8cf7120fc183c12c2d639431482811cd91d 100644
--- a/chrome/browser/shell_integration_win.cc
+++ b/chrome/browser/shell_integration_win.cc
@@ -14,17 +14,22 @@
 #include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/path_service.h"
+#include "base/process/launch.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/timer/timer.h"
 #include "base/win/registry.h"
 #include "base/win/scoped_comptr.h"
 #include "base/win/scoped_propvariant.h"
 #include "base/win/shortcut.h"
 #include "base/win/windows_version.h"
 #include "chrome/browser/policy/policy_path_parser.h"
+#include "chrome/browser/ui/startup/startup_browser_creator.h"
 #include "chrome/browser/web_applications/web_app.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths_internal.h"
@@ -38,6 +43,7 @@
 #include "chrome/installer/util/util_constants.h"
 #include "chrome/installer/util/work_item.h"
 #include "chrome/installer/util/work_item_list.h"
+#include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 
 using content::BrowserThread;
@@ -46,6 +52,10 @@ namespace {
 
 const wchar_t kAppListAppNameSuffix[] = L"AppList";
 
+const char kAsyncSetAsDefaultExperimentName[] = "AsyncSetAsDefault";
+const char kEnableAsyncSetAsDefault[] = "enable-async-set-as-default";
+const char kDisableAsyncSetAsDefault[] = "disable-async-set-as-default";
+
 // Helper function for ShellIntegration::GetAppId to generates profile id
 // from profile path. "profile_id" is composed of sanitized basenames of
 // user data dir and profile dir joined by a ".".
@@ -240,19 +250,60 @@ ShellIntegration::DefaultWebClientState
   }
 }
 
+// Resets the default browser choice for the current user.
+void ResetDefaultBrowser() {
+  static const wchar_t* const kUrlAssociationKeyFormats[] = {
+      L"SOFTWARE\\Microsoft\\Windows\\Shell\\Associations\\UrlAssociations\\"
+      L"%ls\\UserChoice",
+      L"SOFTWARE\\Microsoft\\Windows\\Roaming\\OpenWith\\UrlAssociations\\"
+      L"%ls\\UserChoice"};
+  static const wchar_t* const kProtocols[] = {L"http", L"https"};
+
+  for (const wchar_t* format : kUrlAssociationKeyFormats) {
+    for (const wchar_t* protocol : kProtocols) {
+      base::win::RegKey registry_key(
+          HKEY_CURRENT_USER, base::StringPrintf(format, protocol).c_str(),
+          KEY_SET_VALUE);
+      registry_key.DeleteValue(L"Hash");
+    }
+  }
+}
+
+// Returns true if the AsyncSetAsDefault field trial is activated.
+bool IsAsyncSetAsDefaultEnabled() {
+  using base::CommandLine;
+
+  // Note: It's important to query the field trial state first, to ensure that
+  // UMA reports the correct group.
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("AsyncSetAsDefault");
+  if (CommandLine::ForCurrentProcess()->HasSwitch(kDisableAsyncSetAsDefault))
+    return false;
+  if (CommandLine::ForCurrentProcess()->HasSwitch(kEnableAsyncSetAsDefault))
+    return true;
+
+  return base::StartsWith(group_name, "Enabled", base::CompareCase::SENSITIVE);
+}
+
 }  // namespace
 
+// static
+bool ShellIntegration::IsSetAsDefaultAsynchronous() {
+  return base::win::GetVersion() >= base::win::VERSION_WIN10 &&
+         IsAsyncSetAsDefaultEnabled();
+}
+
 ShellIntegration::DefaultWebClientSetPermission
     ShellIntegration::CanSetAsDefaultBrowser() {
   BrowserDistribution* distribution = BrowserDistribution::GetDistribution();
   if (distribution->GetDefaultBrowserControlPolicy() !=
           BrowserDistribution::DEFAULT_BROWSER_FULL_CONTROL)
     return SET_DEFAULT_NOT_ALLOWED;
-
   if (ShellUtil::CanMakeChromeDefaultUnattended())
     return SET_DEFAULT_UNATTENDED;
-  else
-    return SET_DEFAULT_INTERACTIVE;
+  if (IsSetAsDefaultAsynchronous())
+    return SET_DEFAULT_ASYNCHRONOUS;
+  return SET_DEFAULT_INTERACTIVE;
 }
 
 bool ShellIntegration::SetAsDefaultBrowser() {
@@ -419,8 +470,7 @@ base::string16 ShellIntegration::GetChromiumModelIdForProfile(
 
 base::string16 ShellIntegration::GetAppListAppModelIdForProfile(
     const base::FilePath& profile_path) {
-  return ShellIntegration::GetAppModelIdForProfile(
-      GetAppListAppName(), profile_path);
+  return GetAppModelIdForProfile(GetAppListAppName(), profile_path);
 }
 
 void ShellIntegration::MigrateChromiumShortcuts() {
@@ -588,3 +638,78 @@ base::FilePath ShellIntegration::GetStartMenuShortcut(
 
   return base::FilePath();
 }
+
+// static
+bool ShellIntegration::DefaultWebClientWorker::ShouldReportAttemptResults() {
+  return base::win::GetVersion() >= base::win::VERSION_WIN10 &&
+         IsSetAsDefaultAsynchronous();
+}
+
+bool ShellIntegration::DefaultBrowserWorker::InitializeSetAsDefault() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  if (!IsSetAsDefaultAsynchronous())
+    return false;
+
+  // On Windows 10+, there is no official way to prompt the user to set a
+  // default browser. This is the workaround:
+  // 1. Unregister the default browser.
+  // 2. Open "How to make Chrome my default browser" link with openwith.exe.
+  // 3. Windows will prompt the user with "How would you link to open this?".
+  // 4. If Chrome is selected, we intercept the attempt to open the URL and
+  //    instead call OnSetAsDefaultAttemptComplete(), passing true to indicate
+  //    success.
+  // 5. If Chrome is not selected, the url is opened in the selected browser.
+  //    After a certain amount of time, we notify the observer that the
+  //    process failed.
+
+  if (!StartupBrowserCreator::SetDefaultBrowserCallback(
+          base::Bind(&DefaultBrowserWorker::OnSetAsDefaultAttemptComplete, this,
+                     AttemptResult::SUCCESS))) {
+    // Another worker is currently processing. Note that this will still cause
+    // SetAsDefaultBrowserAsynchronous() to be invoked in SetAsDefault() but
+    // the other worker will happily intercept the attempt.
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&DefaultBrowserWorker::OnSetAsDefaultAttemptComplete, this,
+                   AttemptResult::OTHER_WORKER));
+    return false;
+  }
+
+  // Start the timer.
+  if (!async_timer_)
+    async_timer_.reset(new base::OneShotTimer());
+  std::string value = variations::GetVariationParamValue(
+      kAsyncSetAsDefaultExperimentName, "TimerDuration");
+  int seconds = 0;
+  if (!value.empty())
+    base::StringToInt(value, &seconds);
+  if (!seconds)
+    seconds = 120;  // Default value of 2 minutes.
+  async_timer_->Start(
+      FROM_HERE, base::TimeDelta::FromSeconds(seconds),
+      base::Bind(&DefaultBrowserWorker::OnSetAsDefaultAttemptComplete, this,
+                 AttemptResult::FAILURE));
+  return true;
+}
+
+void ShellIntegration::DefaultBrowserWorker::FinalizeSetAsDefault() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(set_as_default_initialized_);
+
+  async_timer_.reset();
+  StartupBrowserCreator::ClearDefaultBrowserCallback();
+}
+
+// static
+bool ShellIntegration::DefaultBrowserWorker::SetAsDefaultBrowserAsynchronous() {
+  DCHECK(IsSetAsDefaultAsynchronous());
+
+  ResetDefaultBrowser();
+
+  base::CommandLine cmdline(base::FilePath(L"openwith.exe"));
+  cmdline.AppendArgNative(StartupBrowserCreator::GetDefaultBrowserUrl());
+  base::Process process(base::LaunchProcess(cmdline, base::LaunchOptions()));

[grt (UTC plus 2), 2015/10/02 17:39:18]

nit:
  return base::LaunchProcess(cmdline, base::LaunchOptions()).IsValid();

[Patrick Monette, 2015/10/02 20:15:14]

Done.

+
+  return process.IsValid();
+}