Use a valid /prefetch argument when launching a process.

content/browser/ppapi_plugin_process_host.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 "content/browser/ppapi_plugin_process_host.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 20 matching lines @@
 #include "content/public/common/sandbox_type.h"
 #include "content/public/common/sandboxed_process_launcher_delegate.h"
 #include "ipc/ipc_switches.h"
 #include "net/base/network_change_notifier.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ui/base/ui_base_switches.h"
 
 #if defined(OS_WIN)
 #include "content/browser/renderer_host/dwrite_font_proxy_message_filter_win.h"
 #include "content/common/sandbox_win.h"
+#include "content/public/common/prefetch_argument_win.h"
 #include "sandbox/win/src/process_mitigations.h"
 #include "sandbox/win/src/sandbox_policy.h"
 #include "ui/gfx/win/dpi.h"
 #endif
 
 namespace content {
 
 // NOTE: changes to this class need to be reviewed by the security team.
 class PpapiPluginSandboxedProcessLauncherDelegate
     : public content::SandboxedProcessLauncherDelegate {
@@ skipping 310 matching lines @@
     VLOG(1) << "Pepper plugin exe path is empty.";
     return false;
   }
 
   base::CommandLine* cmd_line = new base::CommandLine(exe_path);
   cmd_line->AppendSwitchASCII(switches::kProcessType,
                               is_broker_ ? switches::kPpapiBrokerProcess
                                          : switches::kPpapiPluginProcess);
   cmd_line->AppendSwitchASCII(switches::kProcessChannelID, channel_id);
 
+#if defined(OS_WIN)
+  AddWindowsPrefetchArgument(
+      is_broker_ ? PREFETCH_ID_DEFAULT : PREFETCH_ID_PPAPI, cmd_line);

[gab, 2016/01/21 20:22:59]

What made you decide to have a special ID for one but not the other? Add a
comment explaining why?

+#endif  // defined(OS_WIN)
+
   // These switches are forwarded to both plugin and broker pocesses.
   static const char* kCommonForwardSwitches[] = {
     switches::kVModule
   };
   cmd_line->CopySwitchesFrom(browser_command_line, kCommonForwardSwitches,
                              arraysize(kCommonForwardSwitches));
 
   if (!is_broker_) {
     static const char* kPluginForwardSwitches[] = {
       switches::kDisableSeccompFilterSandbox,
@@ skipping 132 matching lines @@
   // sent_requests_ queue should be the one that the plugin just created.
   Client* client = sent_requests_.front();
   sent_requests_.pop();
 
   const ChildProcessData& data = process_->GetData();
   client->OnPpapiChannelOpened(channel_handle, base::GetProcId(data.handle),
                                data.id);
 }
 
 }  // namespace content