Use a valid /prefetch argument when launching a process.

components/crash/content/app/crashpad_win.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 "components/crash/content/app/crashpad.h"
 
 #include <stddef.h>
 
 #include "base/environment.h"
 #include "base/lazy_instance.h"
@@ skipping 66 matching lines @@
 
     // In test binaries, use crashpad_handler directly. Otherwise, we launch
     // chrome.exe with --type=crashpad-handler.
     base::FilePath exe_file;
     CHECK(PathService::Get(base::FILE_EXE, &exe_file));
     if (exe_file.BaseName().value() != FILE_PATH_LITERAL("chrome.exe")) {
       base::FilePath exe_dir = exe_file.DirName();
       exe_file = exe_dir.Append(FILE_PATH_LITERAL("crashpad_handler.exe"));
     } else {
       arguments.push_back("--type=crashpad-handler");
+
+      // Add a prefetch argument to avoid polluting the prefetch profile of the
+      // browser process.
+      arguments.push_back("/prefetch:8");

[gab, 2016/01/26 21:40:26]

I hate having to use hardcoded strings, why can't this one refer to the constant
like other components do?

At least add a comment reference to kPrefetchArgumentOther?

[fdoray, 2016/01/27 20:12:19]

Done. I was scared of adding the crashpad->content_common dependency. We'll see
what the owners think about it :) I can't add a crashpad->static_switches
dependency, because I get "symbols defined multiple times" errors when crashpad
is linked with targets that already depend on content_common.

[fdoray, 2016/01/28 22:11:06]

Unfortunately, I can't use the constant here.
- The constant is defined in //content/public/common and
//content/public/common:static_switches. 
- //components/html_viewer depends on crashpad and
//content/public/common:static_switches -> symbols defined multiple times if
crashpad depends on //content/public/common
- //chrome/browser depends on crashpad and //content/public/common -> symbols
defined multiple times if crashpad depends on
//content/public/common:static_switches

     }
 
     // TODO(scottmg): See https://crashpad.chromium.org/bug/23.
     arguments.push_back("--no-rate-limit");
 
     result = g_crashpad_client.Get().StartHandler(
         exe_file, database_path, url, process_annotations, arguments, false);
 
     // If we're the browser, push the pipe name into the environment so child
     // processes can connect to it. If we inherited another crashpad_handler's
@@ skipping 168 matching lines @@
 void __declspec(dllexport) __cdecl UnregisterNonABICompliantCodeRange(
     void* start) {
   ExceptionHandlerRecord* record =
       reinterpret_cast<ExceptionHandlerRecord*>(start);
 
   CHECK(RtlDeleteFunctionTable(&record->runtime_function));
 }
 #endif  // ARCH_CPU_X86_64
 
 }  // extern "C"