Upon execution of the App Host, ask Omaha to install the Chrome Binaries if they are not present on…

chrome/browser/extensions/app_host/app_host_main.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 "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/process_util.h"
+#include "chrome/browser/extensions/app_host/binaries_installer.h"
 #include "chrome/installer/launcher_support/chrome_launcher_support.h"
 
-namespace {
-
-const wchar_t kChromeExe[] = L"chrome.exe";
-
-}  // namespace
-
 int main(int /* argc */, char* /* argv[] */) {
   base::AtExitManager exit_manager;
 
   // Initialize the commandline singleton from the environment.
   CommandLine::Init(0, NULL);
 
   FilePath chrome_exe(chrome_launcher_support::GetAnyChromePath());
 
   if (chrome_exe.empty()) {
-    LOG(ERROR) << "No Chrome executable could be found.";
-    // TODO(erikwright): install Chrome.
-    return 1;
+    LOG(INFO) << "No Chrome executable could be found. Let's install it.";

[robertshield, 2012/08/16 13:08:16]

Does the app host / Omaha show any kind of UI while this is happening?

[erikwright (departed), 2012/08/16 21:05:15]

Not at the moment. App Host probably should before a full consumer launch
though.

+    HRESULT hr = app_host::InstallBinaries();
+    if (FAILED(hr)) {
+      LOG(ERROR) << "Failed to install the Chrome Binaries. Error: " << hr;
+      return 1;
+    } else {
+      chrome_exe = chrome_launcher_support::GetAnyChromePath();
+      if (chrome_exe.empty()) {
+        LOG(ERROR) << "Failed to find the Chrome Binaries despite a "
+                   << "'successful' installation.";
+        return 1;
+      }
+    }
   }
 
   CommandLine chrome_exe_command_line(chrome_exe);
   chrome_exe_command_line.AppendArguments(
       *CommandLine::ForCurrentProcess(), false);
 
   if (base::LaunchProcess(chrome_exe_command_line,
                           base::LaunchOptions(),
                           NULL)) {
     LOG(INFO) << "Delegated to Chrome executable at " << chrome_exe.value();
     return 0;
   } else {
     LOG(INFO) << "Failed to launch Chrome executable at " << chrome_exe.value();
     return 1;
   }
 }