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);
 
       if (chrome_frame_state != NULL &&

[gab, 2012/11/16 22:20:26]

This is extremely similar to the code you added below (given it says the same
after applying comments), you can avoid duplicating code without creating a new
method (as creating a method would hinder readability here I feel) by doing
something like (see similar implementation in shell_util.cc:GetProgIdEntries()):

// Uninstall each product of type |type| listed below based on the presence or
absence of |switch| in that product's uninstall command.
const struct {
  BrowserDistribution::Type type;
  const char* switch,
  bool switch_expected;
} conditional_additions[] = {
  // If Chrome Frame is installed in Ready Mode. Remove it along with Chrome.
  { BrowserDistribution::CHROME_FRAME, switches::kChromeFrameReadyMode, true },
  // your comment about the app host....
  { BrowserDistribution::CHROME_APP_HOST, switches::kChromeAppLauncher, false },
};

for (size_t i = 0; i < arraysize(conditional_additions); ++i) {
  // common implementation.
}

[huangs, 2012/11/17 00:15:41]

Done.

           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();
       }
+
+      const ProductState* app_host_state = machine_state.GetProductState(

[gab, 2012/11/16 22:20:26]

Rename variable to make it explicit this is system-level state,
sys_app_host_state? Helps readability I think, I wasn't sure why this was the
case until I looked at the code more (same for chrome_frame_state above please).

[huangs, 2012/11/17 00:15:41]

Disregarding, per F2F.

+          system_install(), BrowserDistribution::CHROME_APP_HOST);
+
+      if (app_host_state != NULL &&
+          !app_host_state->uninstall_command().HasSwitch(
+              switches::kChromeAppLauncher) &&
+          !FindProduct(BrowserDistribution::CHROME_APP_HOST)) {
+        // App Host (non-App Launcher) is installed. Remove it along with
+        // Chrome. If we uninstall system-level Chrome, but user-level
+        // (non-App Launcher) App Host exists, then app_host.exe remains.
+        // When executed, orphaned app_host.exe prompts user for further action.

[gab, 2012/11/16 22:20:26]

What about when uninstalling user-level Chrome with no user-levle app launcher
present?

[huangs, 2012/11/17 00:15:41]

In this case, app_host_state will be NULL, and the block will be ignored.

+        Product* p = AddProductFromPreferences(
+            BrowserDistribution::CHROME_APP_HOST, 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);
 
       if (type == BrowserDistribution::CHROME_BINARIES)
@@ skipping 24 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