adds WARP support to Chromium, for Metro mode only, on Windows 8

chrome/app/chrome_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/app/chrome_main_delegate.h"
 
 #include "content/public/app/content_main.h"
 
 #if defined(OS_WIN)
+#include "base/command_line.h"
 #include "base/debug/dump_without_crashing.h"
 #include "base/win/win_util.h"
 #include "chrome/common/chrome_constants.h"
+#include "chrome/common/chrome_switches.h"
+#include "gpu/config/gpu_info_collector.h"
 
 #define DLLEXPORT __declspec(dllexport)
 
 // We use extern C for the prototype DLLEXPORT to avoid C++ name mangling.
 extern "C" {
 DLLEXPORT int __cdecl ChromeMain(HINSTANCE instance,
                                  sandbox::SandboxInterfaceInfo* sandbox_info);
 }
 #elif defined(OS_POSIX)
 extern "C" {
@@ skipping 19 matching lines @@
   params.sandbox_info = sandbox_info;
 
   // SetDumpWithoutCrashingFunction must be passed the DumpProcess function
   // from the EXE and not from the DLL in order for DumpWithoutCrashing to
   // function correctly.
   typedef void (__cdecl *DumpProcessFunction)();
   DumpProcessFunction DumpProcess = reinterpret_cast<DumpProcessFunction>(
       ::GetProcAddress(::GetModuleHandle(chrome::kBrowserProcessExecutableName),
           "DumpProcessWithoutCrash"));
   base::debug::SetDumpWithoutCrashingFunction(DumpProcess);
+
+  if (CommandLine::InitializedForCurrentProcess()) {
+    gpu::SetShouldFallbackToWarp(
+        CommandLine::ForCurrentProcess()->HasSwitch(switches::kViewerConnect));

[Zhenyao Mo, 2014/08/29 18:28:50]

It seems to me that we add ShouldFallbackToWarp() and SetShouldFallbackToWarp()
in an awkward place rather than gpu_data_manager, simply because the
kViewerConnect lives in chrome, not content.

Is it better to move this switch to the content side?  So the
ShoudFallbackToWarp can have a more natural implementation?

[luken, 2014/08/29 23:34:03]

I moved it. Since kViewerConnect needs to be used by delegate_execute the best
place I could find was ui_base_switches.

+  }
 #else
   params.argc = argc;
   params.argv = argv;
 #endif
 
   int rv = content::ContentMain(params);
 
 #if defined(OS_WIN)
   base::win::SetShouldCrashOnProcessDetach(false);
 #endif
 
   return rv;
 }