Fix registerProtocolHandler implementation on Windows 8 and 10.

chrome/installer/util/shell_util.cc

Index: chrome/installer/util/shell_util.cc
diff --git a/chrome/installer/util/shell_util.cc b/chrome/installer/util/shell_util.cc
index 202d8716381ad6b28dd97721e94f13e3d46e48ef..87346d024ac248d2ff947df805313f767143dbf5 100644
--- a/chrome/installer/util/shell_util.cc
+++ b/chrome/installer/util/shell_util.cc
@@ -80,6 +80,8 @@ enum RegistrationConfirmationLevel {
 };
 
 const wchar_t kReinstallCommand[] = L"ReinstallCommand";
+const wchar_t kSystemSettingsDefaultAppsFormat[] =
+    L"SystemSettings_DefaultApps_%ls";
 
 // Returns the current (or installed) browser's ProgId (e.g.
 // "ChromeHTML|suffix|").
@@ -709,24 +711,29 @@ bool ElevateAndRegisterChrome(BrowserDistribution* dist,
 
 // Launches the Windows 'settings' modern app with the 'default apps' view
 // focused. This only works for Windows 8 and Windows 10. The appModelId
-// looks arbitrary but it is the same in Win8 and Win10 previews. There
-// is no easy way to retrieve the appModelId from the registry.
-bool LaunchDefaultAppsSettingsModernDialog() {
+// looks arbitrary but it is the same in Win8 and Win10. There is no easy way to
+// retrieve the appModelId from the registry.
+bool LaunchDefaultAppsSettingsModernDialog(const wchar_t* target) {

[grt (UTC plus 2), 2016/04/15 18:47:26]

how about having this take the protocol rather than a target? it can take care
of the mapping of http and mailto to specific targets.

[Patrick Monette, 2016/04/15 21:35:42]

Done.

+  DCHECK(target);
+  static const wchar_t kControlPanelAppModelId[] =
+      L"windows.immersivecontrolpanel_cw5n1h2txyewy"
+      L"!microsoft.windows.immersivecontrolpanel";
+
   base::win::ScopedComPtr<IApplicationActivationManager> activator;
   HRESULT hr = activator.CreateInstance(CLSID_ApplicationActivationManager);
   if (SUCCEEDED(hr)) {
     DWORD pid = 0;
     CoAllowSetForegroundWindow(activator.get(), nullptr);
-    hr = activator->ActivateApplication(
-        L"windows.immersivecontrolpanel_cw5n1h2txyewy"
-        L"!microsoft.windows.immersivecontrolpanel",
-        L"page=SettingsPageAppsDefaults", AO_NONE, &pid);
+    hr = activator->ActivateApplication(kControlPanelAppModelId,
+                                        L"page=SettingsPageAppsDefaults",
+                                        AO_NONE, &pid);
     if (SUCCEEDED(hr)) {
       hr = activator->ActivateApplication(
-          L"windows.immersivecontrolpanel_cw5n1h2txyewy"
-          L"!microsoft.windows.immersivecontrolpanel",
-          L"page=SettingsPageAppsDefaults"
-          L"&target=SystemSettings_DefaultApps_Browser", AO_NONE, &pid);
+          kControlPanelAppModelId,
+          base::StringPrintf(L"page=SettingsPageAppsDefaults&target=%ls",
+                             target)
+              .c_str(),
+          AO_NONE, &pid);
     }
     if (SUCCEEDED(hr))
       return true;
@@ -1343,6 +1350,28 @@ bool RemoveShortcutFolderIfEmpty(ShellUtil::ShortcutLocation location,
   return true;
 }
 
+// Returns the target used as a activate parameter when opening the settings
+// pointing to the page that is the most relevant to a user trying to change the
+// default handler for |protocol|.
+base::string16 GetTargetForDefaultAppsSettings(const base::string16& protocol) {
+  if (protocol == L"mailto")
+    return base::StringPrintf(kSystemSettingsDefaultAppsFormat, L"Email");
+
+  return L"SettingsPageAppsDefaultsProtocolView";
+}
+
+// Creates the registry key <root hkey>\Software\Classes\<protocol>\URL Protocol
+// so that Windows allows the handler for this |protocol| to be be changed.
+bool CreateKeyForProtocol(const wchar_t* protocol) {
+  RegKey reg_key(HKEY_CURRENT_USER, ShellUtil::kRegClasses, KEY_ALL_ACCESS);
+  DCHECK(reg_key.Valid());
+  if (reg_key.CreateKey(protocol, KEY_CREATE_SUB_KEY | KEY_SET_VALUE) !=
+      ERROR_SUCCESS)
+    return false;
+
+  return reg_key.WriteValue(ShellUtil::kRegUrlProtocol, L"") == ERROR_SUCCESS;
+}
+
 }  // namespace
 
 const wchar_t* ShellUtil::kRegDefaultIcon = L"\\DefaultIcon";
@@ -1815,6 +1844,17 @@ bool ShellUtil::CanMakeChromeDefaultUnattended() {
   return base::win::GetVersion() < base::win::VERSION_WIN8;
 }
 
+// static
+ShellUtil::SetDefaultInteractiveMode ShellUtil::GetSetDefaultInteractiveMode() {
+  DCHECK(!CanMakeChromeDefaultUnattended());
+
+  if (base::win::GetVersion() == base::win::VERSION_WIN8) {

[grt (UTC plus 2), 2016/04/15 18:47:26]

nit: omit braces

[Patrick Monette, 2016/04/15 21:35:42]

Done.

+    return SetDefaultInteractiveMode::INTENT_PICKER;
+  }
+
+  return SetDefaultInteractiveMode::SYSTEM_SETTINGS;
+}
+
 bool ShellUtil::MakeChromeDefault(BrowserDistribution* dist,
                                   int shell_change,
                                   const base::FilePath& chrome_exe,
@@ -1888,7 +1928,7 @@ bool ShellUtil::MakeChromeDefault(BrowserDistribution* dist,
 bool ShellUtil::ShowMakeChromeDefaultSystemUI(
     BrowserDistribution* dist,
     const base::FilePath& chrome_exe) {
-  DCHECK_GE(base::win::GetVersion(), base::win::VERSION_WIN8);
+  DCHECK(!CanMakeChromeDefaultUnattended());
   if (dist->GetDefaultBrowserControlPolicy() !=
       BrowserDistribution::DEFAULT_BROWSER_FULL_CONTROL) {
     return false;
@@ -1900,22 +1940,27 @@ bool ShellUtil::ShowMakeChromeDefaultSystemUI(
   bool succeeded = true;
   bool is_default = (GetChromeDefaultState() == IS_DEFAULT);
   if (!is_default) {
-    if (base::win::GetVersion() < base::win::VERSION_WIN10) {
-      // On Windows 8, you can't set yourself as the default handler
-      // programatically. In other words IApplicationAssociationRegistration
-      // has been rendered useless. What you can do is to launch
-      // "Set Program Associations" section of the "Default Programs"
-      // control panel, which is a mess, or pop the concise "How you want to
-      // open webpages?" dialog.  We choose the latter.
-      ScopedUserProtocolEntry user_protocol_entry;
-      succeeded = LaunchSelectDefaultProtocolHandlerDialog(L"http");
-    } else {
-      // On Windows 10, you can't even launch the associations dialog.
-      // So we launch the settings dialog. Quoting from MSDN: "The Open With
-      // dialog box can no longer be used to change the default program used to
-      // open a file extension. You can only use SHOpenWithDialog to open
-      // a single file."
-      succeeded = LaunchDefaultAppsSettingsModernDialog();
+    switch (GetSetDefaultInteractiveMode()) {
+      case INTENT_PICKER: {
+        // On Windows 8, you can't set yourself as the default handler
+        // programatically. In other words IApplicationAssociationRegistration
+        // has been rendered useless. What you can do is to launch
+        // "Set Program Associations" section of the "Default Programs"
+        // control panel, which is a mess, or pop the concise "How you want to
+        // open webpages?" dialog.  We choose the latter.
+        ScopedUserProtocolEntry user_protocol_entry;
+        succeeded = LaunchSelectDefaultProtocolHandlerDialog(L"http");
+      } break;

[grt (UTC plus 2), 2016/04/15 18:47:26]

is this what git cl format likes?

[Patrick Monette, 2016/04/15 21:35:42]

Yes.

+      case SYSTEM_SETTINGS:
+        // On Windows 10, you can't even launch the associations dialog.
+        // So we launch the settings dialog. Quoting from MSDN: "The Open With
+        // dialog box can no longer be used to change the default program used
+        // to open a file extension. You can only use SHOpenWithDialog to open
+        // a single file."
+        succeeded = LaunchDefaultAppsSettingsModernDialog(
+            base::StringPrintf(kSystemSettingsDefaultAppsFormat, L"Browser")

[grt (UTC plus 2), 2016/04/15 18:47:26]

how about using GetTargetForDefaultAppsSettings(L"http") for this? as a benefit,
kSystemSettingsDefaultAppsFormat can be moved into the function.

[Patrick Monette, 2016/04/15 21:35:42]

Done.

+                .c_str());
+        break;
     }
     is_default = (succeeded && GetChromeDefaultState() == IS_DEFAULT);
   }
@@ -1977,7 +2022,7 @@ bool ShellUtil::ShowMakeChromeDefaultProtocolClientSystemUI(
     BrowserDistribution* dist,
     const base::FilePath& chrome_exe,
     const base::string16& protocol) {
-  DCHECK_GE(base::win::GetVersion(), base::win::VERSION_WIN8);
+  DCHECK(!CanMakeChromeDefaultUnattended());
   if (dist->GetDefaultBrowserControlPolicy() !=
       BrowserDistribution::DEFAULT_BROWSER_FULL_CONTROL) {
     return false;
@@ -1987,17 +2032,36 @@ bool ShellUtil::ShowMakeChromeDefaultProtocolClientSystemUI(
            dist, chrome_exe, base::string16(), protocol, true))
     return false;
 
+  // This registry key is required so Windows give the user the possibility to
+  // choose a default handler for |protocol|.
+  if (!CreateKeyForProtocol(protocol.c_str())) {

[grt (UTC plus 2), 2016/04/15 18:47:26]

is this doing the same thing that the ScopedUserProtocolEntry does? can you
generalize that and use it here?

[Patrick Monette, 2016/04/15 21:35:42]

Good point! I generalized it for all protocols so I can use it for the win8 path
here. For the win10 path, the better scope is the OpenSystemSettingsHelper so I
moved it there.

+    DVLOG(1) << "Failed to create a valid key for the protocol " << protocol;
+    return false;
+  }
+
   bool succeeded = true;
   bool is_default = (
       GetChromeDefaultProtocolClientState(protocol) == IS_DEFAULT);
   if (!is_default) {
-    // On Windows 8, you can't set yourself as the default handler
-    // programatically. In other words IApplicationAssociationRegistration
-    // has been rendered useless. What you can do is to launch
-    // "Set Program Associations" section of the "Default Programs"
-    // control panel, which is a mess, or pop the concise "How you want to open
-    // links of this type (protocol)?" dialog.  We choose the latter.
-    succeeded = LaunchSelectDefaultProtocolHandlerDialog(protocol.c_str());
+    switch (GetSetDefaultInteractiveMode()) {
+      case INTENT_PICKER: {
+        // On Windows 8, you can't set yourself as the default handler
+        // programatically. In other words IApplicationAssociationRegistration
+        // has been rendered useless. What you can do is to launch
+        // "Set Program Associations" section of the "Default Programs"
+        // control panel, which is a mess, or pop the concise "How you want to
+        // open
+        // links of this type (protocol)?" dialog.  We choose the latter.
+        ScopedUserProtocolEntry user_protocol_entry;

[grt (UTC plus 2), 2016/04/15 18:47:26]

as-is, this is specifically for http, so it isn't needed here, unless it's
suitable to be generalized as per my comment above.

[Patrick Monette, 2016/04/15 21:35:41]

Done.

+        succeeded = LaunchSelectDefaultProtocolHandlerDialog(protocol.c_str());
+      } break;
+      case SYSTEM_SETTINGS:
+        // On Windows 10, you can't even launch the associations dialog.
+        // So we launch the settings dialog.
+        succeeded = LaunchDefaultAppsSettingsModernDialog(
+            GetTargetForDefaultAppsSettings(protocol).c_str());
+        break;
+    }
     is_default = (succeeded &&
                   GetChromeDefaultProtocolClientState(protocol) == IS_DEFAULT);
   }