Implementing --app-launcher install/uninstall flow.

chrome/installer/setup/setup_main.cc

Index: chrome/installer/setup/setup_main.cc
diff --git a/chrome/installer/setup/setup_main.cc b/chrome/installer/setup/setup_main.cc
index 4c17a1cb95eb4ab9c91abf86b215af3c6603e476..27791790ba91abfe5436bc9c7b6cc792bf85e65a 100644
--- a/chrome/installer/setup/setup_main.cc
+++ b/chrome/installer/setup/setup_main.cc
@@ -361,6 +361,9 @@ bool CheckMultiInstallConditions(const InstallationState& original_state,
     const ProductState* chrome_state =
         original_state.GetProductState(system_level,
                                        BrowserDistribution::CHROME_BROWSER);
+    const ProductState* app_host_state =
+        original_state.GetProductState(system_level,
+                                       BrowserDistribution::CHROME_APP_HOST);
 
     if (!binaries) {
       // This will only be hit if --multi-install is given with no products, or
@@ -452,6 +455,20 @@ bool CheckMultiInstallConditions(const InstallationState& original_state,
           IDS_INSTALL_NON_MULTI_INSTALLATION_EXISTS_BASE, NULL);
       return false;
     }
+
+    if (app_host) {
+      // TODO(huangs): Revisit all these once App Launcher is default.
+      if (app_host_state) {
+        const installer::ChannelInfo& channel_info(app_host_state->channel());

[grt (UTC plus 2), 2012/10/25 14:46:53]

same here: don't use the channel info for this.  check uninstall_command() for
the switch you care about.

[huangs, 2012/10/29 21:15:16]

Done.

+        if (channel_info.IsAppLauncher() &&
+            !app_host->HasOption(installer::kOptionAppLauncher)) {
+          LOG(ERROR) << "Cannot downgrade from App Launcher to App Host";
+          *status = installer::HIGHER_VERSION_EXISTS;

[grt (UTC plus 2), 2012/10/25 14:46:53]

please introduce a new code rather than overloading an existing one.

[huangs, 2012/10/29 21:15:16]

Not doing this anymore, so moot.

+          return false;
+        }
+      }
+    }
+
   } else {
     // This is a non-multi installation.
 
@@ -1431,7 +1448,11 @@ int WINAPI wWinMain(HINSTANCE instance, HINSTANCE prev_instance,
   original_state.Initialize();
 
   InstallerState installer_state;
-  installer_state.Initialize(cmd_line, prefs, original_state);
+  if (!installer_state.Initialize(cmd_line, prefs, original_state)) {
+    LOG(ERROR) << "Conflicting options are found.";
+    // TODO(huangs): Find better error code!
+    return installer::INSTALL_FAILED;
+  }
   const bool is_uninstall = cmd_line.HasSwitch(installer::switches::kUninstall);
 
   // Check to make sure current system is WinXP or later. If not, log