Uninstall Chrome + has App Host + not App Launcher => Uninstall App Host.

chrome/installer/util/installer_state.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/installer/util/installer_state.h"
 
 #include <algorithm>
 #include <functional>
 #include <utility>
 
@@ skipping 101 matching lines @@
 
   if (!prefs.GetBool(master_preferences::kMsi, &msi_))
     msi_ = false;
 
   ensure_google_update_present_ =
       command_line.HasSwitch(installer::switches::kEnsureGoogleUpdatePresent);
 
   const bool is_uninstall = command_line.HasSwitch(switches::kUninstall);
 
   if (prefs.install_chrome()) {
-    Product* p =
-        AddProductFromPreferences(BrowserDistribution::CHROME_BROWSER, prefs,
-                                  machine_state);
+    Product* p = AddProductFromPreferences(
+        BrowserDistribution::CHROME_BROWSER, prefs, machine_state);
     VLOG(1) << (is_uninstall ? "Uninstall" : "Install")
             << " distribution: " << p->distribution()->GetAppShortCutName();
   }
   if (prefs.install_chrome_frame()) {
-    Product* p =
-        AddProductFromPreferences(BrowserDistribution::CHROME_FRAME, prefs,
-                                  machine_state);
+    Product* p = AddProductFromPreferences(
+        BrowserDistribution::CHROME_FRAME, prefs, machine_state);
     VLOG(1) << (is_uninstall ? "Uninstall" : "Install")
             << " distribution: " << p->distribution()->GetAppShortCutName();
   }
+
   if (prefs.install_chrome_app_host()) {
-    Product* p =
-        AddProductFromPreferences(BrowserDistribution::CHROME_APP_HOST, prefs,
-                                  machine_state);
+    Product* p = AddProductFromPreferences(
+        BrowserDistribution::CHROME_APP_HOST, prefs, machine_state);
     VLOG(1) << (is_uninstall ? "Uninstall" : "Install")
             << " distribution: " << p->distribution()->GetAppShortCutName();
   }
 
   if (!is_uninstall && is_multi_install()) {
     bool need_binaries = false;
     if (FindProduct(BrowserDistribution::CHROME_APP_HOST)) {
       // App Host will happily use Chrome at system level, or binaries at system
       // level, even if app host is user level.
       const ProductState* chrome_state = machine_state.GetProductState(
@@ skipping 11 matching lines @@
 
     // Chrome/Chrome Frame multi need Binaries at their own level.
     if (FindProduct(BrowserDistribution::CHROME_BROWSER))
       need_binaries = true;
 
     if (FindProduct(BrowserDistribution::CHROME_FRAME))
       need_binaries = true;
 
     if (need_binaries && !FindProduct(BrowserDistribution::CHROME_BINARIES)) {
       // Force binaries to be installed/updated.
-      Product* p =
-          AddProductFromPreferences(BrowserDistribution::CHROME_BINARIES,
-                                    prefs,
-                                    machine_state);
+      Product* p = AddProductFromPreferences(
+          BrowserDistribution::CHROME_BINARIES, prefs, machine_state);
       VLOG(1) << "Install distribution: "
               << p->distribution()->GetAppShortCutName();
     }
   }
 
   if (is_uninstall && prefs.is_multi_install()) {
     if (FindProduct(BrowserDistribution::CHROME_BROWSER)) {
-      const ProductState* chrome_frame_state = machine_state.GetProductState(
-          system_install(), BrowserDistribution::CHROME_FRAME);
+      // Uninstall each product of type |type| listed below based on the
+      // presence or absence of |switch_name| in that product's uninstall
+      // command.
+      const struct {
+        BrowserDistribution::Type type;
+        const char* switch_name;
+        bool switch_expected;
+      } conditional_additions[] = {
+        // If Chrome Frame is installed in Ready Mode, remove it with Chrome.
+        { BrowserDistribution::CHROME_FRAME,
+          switches::kChromeFrameReadyMode,
+          true },
+        // If the App Host is installed, but not the App Launcher, remove it
+        // with Chrome. Note however that for system-level Chrome uninstalls,
+        // any installed user-level App Host will remain even if there is no
+        // App Launcher present (the orphaned app_host.exe will prompt the user
+        // for further action when executed).
+        { BrowserDistribution::CHROME_APP_HOST,
+          switches::kChromeAppLauncher,
+          false },
+      };
 
-      if (chrome_frame_state != NULL &&
-          chrome_frame_state->uninstall_command().HasSwitch(
-              switches::kChromeFrameReadyMode) &&
-          !FindProduct(BrowserDistribution::CHROME_FRAME)) {
-        // Chrome Frame is installed in Ready Mode. Remove it along with Chrome.
-        Product* p = AddProductFromPreferences(
-            BrowserDistribution::CHROME_FRAME, prefs, machine_state);
-
-        VLOG(1) << "Uninstall distribution: "
-                << p->distribution()->GetAppShortCutName();
+      for (size_t i = 0; i < arraysize(conditional_additions); ++i) {
+        const ProductState* product_state = machine_state.GetProductState(
+            system_install(), conditional_additions[i].type);
+        if (product_state != NULL &&
+            product_state->uninstall_command().HasSwitch(
+                conditional_additions[i].switch_name) ==
+                    conditional_additions[i].switch_expected &&
+            !FindProduct(conditional_additions[i].type)) {
+          Product* p = AddProductFromPreferences(
+              conditional_additions[i].type, prefs, machine_state);
+          VLOG(1) << "Uninstall distribution: "
+                  << p->distribution()->GetAppShortCutName();
+        }
       }
     }
 
     bool keep_binaries = false;
     // Look for a product that is not the binaries and that is not being
     // uninstalled. If not found, binaries are uninstalled too.
     for (size_t i = 0; i < BrowserDistribution::NUM_TYPES; ++i) {
       BrowserDistribution::Type type =
           static_cast<BrowserDistribution::Type>(i);
 
@@ skipping 25 matching lines @@
             keep_binaries = true;
             break;
           }
 
         }
       }
 
       // The product is being uninstalled.
     }
     if (!keep_binaries) {
-      Product* p =
-          AddProductFromPreferences(BrowserDistribution::CHROME_BINARIES, prefs,
-                                    machine_state);
+      Product* p = AddProductFromPreferences(
+          BrowserDistribution::CHROME_BINARIES, prefs, machine_state);
       VLOG(1) << (is_uninstall ? "Uninstall" : "Install")
               << " distribution: " << p->distribution()->GetAppShortCutName();
     }
   }
 
   BrowserDistribution* operand = NULL;
 
   if (is_uninstall) {
     operation_ = UNINSTALL;
   } else if (!prefs.is_multi_install()) {
@@ skipping 511 matching lines @@
   if (is_multi_install()) {
     InstallUtil::AddInstallerResultItems(
         system_install, multi_package_binaries_distribution()->GetStateKey(),
         status, string_resource_id, launch_cmd, install_list.get());
   }
   if (!install_list->Do())
     LOG(ERROR) << "Failed to record installer error information in registry.";
 }
 
 }  // namespace installer