headless: Switch to multiprocess mode by default

headless/lib/headless_content_main_delegate.cc

 // Copyright 2015 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 "headless/lib/headless_content_main_delegate.h"
 
 #include "base/command_line.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 23 matching lines @@
 }
 
 HeadlessContentMainDelegate::~HeadlessContentMainDelegate() {
   DCHECK(g_current_headless_content_main_delegate == this);
   g_current_headless_content_main_delegate = nullptr;
 }
 
 bool HeadlessContentMainDelegate::BasicStartupComplete(int* exit_code) {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
 
-  command_line->AppendSwitch(switches::kNoSandbox);
-  command_line->AppendSwitch(switches::kSingleProcess);
+  if (browser_->options().single_process_mode)
+    command_line->AppendSwitch(switches::kSingleProcess);
 
   // The headless backend is automatically chosen for a headless build, but also
   // adding it here allows us to run in a non-headless build too.
   command_line->AppendSwitchASCII(switches::kOzonePlatform, "headless");
 
   // TODO(skyostil): Investigate using Mesa/SwiftShader for output.
   command_line->AppendSwitch(switches::kDisableGpu);
 
   SetContentClient(&content_client_);
   return false;
@@ skipping 59 matching lines @@
   return renderer_client_.get();
 }
 
 content::ContentUtilityClient*
 HeadlessContentMainDelegate::CreateContentUtilityClient() {
   utility_client_.reset(new HeadlessContentUtilityClient);
   return utility_client_.get();
 }
 
 }  // namespace headless