Make PNaCl component downloadable for chromeos-chrome built for Linux

chrome/browser/chrome_browser_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 "chrome/browser/chrome_browser_main.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 384 matching lines @@
       g_browser_process->component_updater();
 
   // Registration can be before or after cus->Start() so it is ok to post
   // a task to the UI thread to do registration once you done the necessary
   // file IO to know you existing component version.
 #if !defined(OS_CHROMEOS) && !defined(OS_ANDROID)
   RegisterRecoveryComponent(cus, g_browser_process->local_state());
   RegisterPepperFlashComponent(cus);
   RegisterSwiftShaderComponent(cus);
   RegisterWidevineCdmComponent(cus);
-#if !defined(DISABLE_NACL)
-  g_browser_process->pnacl_component_installer()->RegisterPnaclComponent(cus);
 #endif
+
+#if !defined(DISABLE_NACL) && !defined(OS_ANDROID)
+#if defined(OS_CHROMEOS)
+  // PNaCl on Chrome OS is on rootfs and there is no need to download it. But
+  // Chrome4ChromeOS on Linux doesn't contain PNaCl so enable component
+  // installer when ruining on Linux. See crbug.com/422121 for more details.
+  if (!base::SysInfo::IsRunningOnChromeOS())
+#endif
+    g_browser_process->pnacl_component_installer()->RegisterPnaclComponent(cus);
 #endif
 
   if (translate::CldDataSource::ShouldRegisterForComponentUpdates()) {
     RegisterCldComponent(cus);
   }
 
   base::FilePath path;
   if (PathService::Get(chrome::DIR_USER_DATA, &path)) {
 #if defined(OS_ANDROID)
     // The CRLSet component was enabled for some releases. This code attempts to
@@ skipping 1258 matching lines @@
   chromeos::CrosSettings::Shutdown();
 #endif
 #endif
 }
 
 // Public members:
 
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }