Improve Windows GN build setup.

tools/gn/secondary/build/toolchain/win/BUILD.gn

 # Copyright (c) 2013 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.
 
 # Should only be running on Windows.
 assert(is_win)
 
 # Setup the Visual Studio state.
 #
 # Its argument is the location to write the environment files.
 # It will write "environment.x86" and "environment.x64" to this directory,
 # and return a list to us.
 #
 # The list contains the include path as its only element. (I'm expecting to
 # add more so it's currently a list inside a list.)
-msvc_config = [["foo"]]
 #exec_script("get_msvc_config.py",
                      #     [relative_root_output_dir],
                      #     "value")
 
+# This will save the environment block and and copy the gyp-win-tool to the
+# build directory. We pass in the source file of the win tool.
+gyp_win_tool_source =
+  rebase_path("//tools/gyp/pylib/gyp/win_tool.py", ".", root_build_dir)
+exec_script("setup_toolchain.py", [ gyp_win_tool_source ], "value")
+
 # 32-bit toolchain -------------------------------------------------------------
 
 toolchain("32") {
   # Make these apply to all tools below.
   lib_prefix = ""
   lib_dir_prefix="/LIBPATH:"
 
   tool("cc") {
-    command = "ninja -t msvc -e \$arch -- cl.exe /nologo /showIncludes /FC @\$out.rsp /c \$in /Fo\$out /Fd\$pdbname"
+    command = "ninja -t msvc -e environment.x86 -- cl.exe /nologo /showIncludes /FC @\$out.rsp /c \$in /Fo\$out /Fd\$pdbname"
     description = "CC \$out"
     rspfile = "\$out.rsp"
     rspfile_content = "\$defines \$includes \$cflags \$cflags_c"
     deps = "msvc"
   }
   tool("cxx") {
-    command = "ninja -t msvc -e \$arch -- cl.exe /nologo /showIncludes /FC @\$out.rsp /c \$in /Fo\$out /Fd\$pdbname"
+    command = "ninja -t msvc -e environment.x86 -- cl.exe /nologo /showIncludes /FC @\$out.rsp /c \$in /Fo\$out /Fd\$pdbname"
     description = "CXX \$out"
     rspfile = "\$out.rsp"
     rspfile_content = "\$defines \$includes \$cflags \$cflags_cc"
     deps = "msvc"
   }
   #tool("idl") {
-  #  command = $python_path gyp-win-tool midl-wrapper \$arch \$outdir \$tlb \$h \$dlldata \$iid \$
+  #  command = $python_path gyp-win-tool midl-wrapper environment.x86 \$outdir \$tlb \$h \$dlldata \$iid \$
   #      \$proxy \$in \$idlflags
   #  description = IDL \$in
   #}
   tool("rc") {
-    command = "$python_path gyp-win-tool rc-wrapper \$arch rc.exe \$defines \$includes \$rcflags /fo\$out \$in"
+    command = "$python_path gyp-win-tool rc-wrapper environment.x86 rc.exe \$defines \$includes \$rcflags /fo\$out \$in"
     description = "RC \$in"
   }
   #tool("asm") {
-  #  command = $python_path gyp-win-tool asm-wrapper \$arch ml.exe \$defines \$includes /c /Fo \$
+  #  command = $python_path gyp-win-tool asm-wrapper environment.x86 ml.exe \$defines \$includes /c /Fo \$
   #      \$out \$in
   #  description = ASM \$in
   #}
   tool("alink") {
-    command = "$python_path gyp-win-tool link-wrapper \$arch lib.exe /nologo /ignore:4221 /OUT:\$out @\$out.rsp"
+    command = "$python_path gyp-win-tool link-wrapper environment.x86 lib.exe /nologo /ignore:4221 /OUT:\$out @\$out.rsp"
     description = "LIB \$out"
     rspfile = "\$out.rsp"
     rspfile_content = "\$in_newline \$libflags"
   }
   #tool("solink_embed_inc") {
-  #  command = cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo \$implibflag \$
+  #  command = cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo \$implibflag \$
   #      /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp && $python_path gyp-win-tool \$
-  #      manifest-wrapper \$arch cmd /c if exist \$dll.manifest del \$dll.manifest && \$
-  #      $python_path gyp-win-tool manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests \$
-  #      -out:\$dll.manifest && $python_path gyp-win-tool manifest-to-rc \$arch \$dll.manifest \$
-  #      \$dll.manifest.rc 2 && $python_path gyp-win-tool rc-wrapper \$arch rc.exe \$
-  #      \$dll.manifest.rc && $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo \$
+  #      manifest-wrapper environment.x86 cmd /c if exist \$dll.manifest del \$dll.manifest && \$
+  #      $python_path gyp-win-tool manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests \$
+  #      -out:\$dll.manifest && $python_path gyp-win-tool manifest-to-rc environment.x86 \$dll.manifest \$
+  #      \$dll.manifest.rc 2 && $python_path gyp-win-tool rc-wrapper environment.x86 rc.exe \$
+  #      \$dll.manifest.rc && $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo \$
   #      \$implibflag /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp \$dll.manifest.res
   #  description = LINK_EMBED_INC(DLL) \$dll
   #  restat = 1
   #  rspfile = \$dll.rsp
   #  rspfile_content = \$libs \$in_newline \$ldflags
   #}
   #tool("solink_module_embed_inc") {
-  #  command = cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo \$implibflag \$
+  #  command = cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo \$implibflag \$
   #      /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp && $python_path gyp-win-tool \$
-  #      manifest-wrapper \$arch cmd /c if exist \$dll.manifest del \$dll.manifest && \$
-  #      $python_path gyp-win-tool manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests \$
-  #      -out:\$dll.manifest && $python_path gyp-win-tool manifest-to-rc \$arch \$dll.manifest \$
-  #      \$dll.manifest.rc 2 && $python_path gyp-win-tool rc-wrapper \$arch rc.exe \$
-  #      \$dll.manifest.rc && $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo \$
+  #      manifest-wrapper environment.x86 cmd /c if exist \$dll.manifest del \$dll.manifest && \$
+  #      $python_path gyp-win-tool manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests \$
+  #      -out:\$dll.manifest && $python_path gyp-win-tool manifest-to-rc environment.x86 \$dll.manifest \$
+  #      \$dll.manifest.rc 2 && $python_path gyp-win-tool rc-wrapper environment.x86 rc.exe \$
+  #      \$dll.manifest.rc && $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo \$
   #      \$implibflag /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp \$dll.manifest.res
   #  description = LINK_EMBED_INC(DLL) \$dll
   #  restat = 1
   #  rspfile = \$dll.rsp
   #  rspfile_content = \$libs \$in_newline \$ldflags
   #}
   #rule link_embed_inc
-  #  command = cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo /OUT:\$out \$
-  #      /PDB:\$out.pdb @\$out.rsp && $python_path gyp-win-tool manifest-wrapper \$arch cmd /c \$
+  #  command = cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo /OUT:\$out \$
+  #      /PDB:\$out.pdb @\$out.rsp && $python_path gyp-win-tool manifest-wrapper environment.x86 cmd /c \$
   #      if exist \$out.manifest del \$out.manifest && $python_path gyp-win-tool \$
-  #      manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests -out:\$out.manifest && \$
-  #      $python_path gyp-win-tool manifest-to-rc \$arch \$out.manifest \$out.manifest.rc 1 && \$
-  #      $python_path gyp-win-tool rc-wrapper \$arch rc.exe \$out.manifest.rc && \$
-  #      $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo /OUT:\$out /PDB:\$out.pdb \$
+  #      manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests -out:\$out.manifest && \$
+  #      $python_path gyp-win-tool manifest-to-rc environment.x86 \$out.manifest \$out.manifest.rc 1 && \$
+  #      $python_path gyp-win-tool rc-wrapper environment.x86 rc.exe \$out.manifest.rc && \$
+  #      $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo /OUT:\$out /PDB:\$out.pdb \$
   #      @\$out.rsp \$out.manifest.res
   #  description = LINK_EMBED_INC \$out
   #  rspfile = \$out.rsp
   #  rspfile_content = \$in_newline \$libs \$ldflags
   #rule solink_embed
-  #  command = cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo \$implibflag \$
+  #  command = cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo \$implibflag \$
   #      /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp && $python_path gyp-win-tool \$
-  #      manifest-wrapper \$arch cmd /c if exist \$dll.manifest del \$dll.manifest && \$
-  #      $python_path gyp-win-tool manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests \$
+  #      manifest-wrapper environment.x86 cmd /c if exist \$dll.manifest del \$dll.manifest && \$
+  #      $python_path gyp-win-tool manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests \$
   #      -outputresource:\$dll;2
   #  description = LINK_EMBED(DLL) \$dll
   #  restat = 1
   #  rspfile = \$dll.rsp
   #  rspfile_content = \$libs \$in_newline \$ldflags
   #rule solink_module_embed
-  #  command = cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo \$implibflag \$
+  #  command = cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo \$implibflag \$
   #      /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp && $python_path gyp-win-tool \$
-  #      manifest-wrapper \$arch cmd /c if exist \$dll.manifest del \$dll.manifest && \$
-  #      $python_path gyp-win-tool manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests \$
+  #      manifest-wrapper environment.x86 cmd /c if exist \$dll.manifest del \$dll.manifest && \$
+  #      $python_path gyp-win-tool manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests \$
   #      -outputresource:\$dll;2
   #  description = LINK_EMBED(DLL) \$dll
   #  restat = 1
   #  rspfile = \$dll.rsp
   #  rspfile_content = \$libs \$in_newline \$ldflags
   #rule link_embed
-  #  command = cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo /OUT:\$out \$
-  #      /PDB:\$out.pdb @\$out.rsp && $python_path gyp-win-tool manifest-wrapper \$arch cmd /c \$
+  #  command = cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo /OUT:\$out \$
+  #      /PDB:\$out.pdb @\$out.rsp && $python_path gyp-win-tool manifest-wrapper environment.x86 cmd /c \$
   #      if exist \$out.manifest del \$out.manifest && $python_path gyp-win-tool \$
-  #      manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests -outputresource:\$out;1
+  #      manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests -outputresource:\$out;1
   #  description = LINK_EMBED \$out
   #  rspfile = \$out.rsp
   #  rspfile_content = \$in_newline \$libs \$ldflags
   tool("solink") {
-    command = "cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo \$implibflag /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp && $python_path gyp-win-tool manifest-wrapper \$arch cmd /c if exist \$dll.manifest del \$dll.manifest && $python_path gyp-win-tool manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests -out:\$dll.manifest"
+    command = "cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo \$implibflag /DLL /OUT:\$dll /PDB:\$dll.pdb @\$dll.rsp && $python_path gyp-win-tool manifest-wrapper environment.x86 cmd /c if exist \$dll.manifest del \$dll.manifest && $python_path gyp-win-tool manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests -out:\$dll.manifest"
     description = "LINK(DLL) \$dll"
     restat = "1"
     rspfile = "\$dll.rsp"
     rspfile_content = "\$libs \$in_newline \$ldflags"
   }
   tool("link") {
-    command = "cmd /c $python_path gyp-win-tool link-wrapper \$arch link.exe /nologo /OUT:\$out /PDB:\$out.pdb @\$out.rsp && $python_path gyp-win-tool manifest-wrapper \$arch cmd /c if exist \$out.manifest del \$out.manifest && $python_path gyp-win-tool manifest-wrapper \$arch mt.exe -nologo -manifest \$manifests -out:\$out.manifest"
+    command = "cmd /c $python_path gyp-win-tool link-wrapper environment.x86 link.exe /nologo /OUT:\$out /PDB:\$out.pdb @\$out.rsp && $python_path gyp-win-tool manifest-wrapper environment.x86 cmd /c if exist \$out.manifest del \$out.manifest && $python_path gyp-win-tool manifest-wrapper environment.x86 mt.exe -nologo -manifest \$manifests -out:\$out.manifest"
     description = "LINK \$out"
     rspfile = "\$out.rsp"
     rspfile_content = "\$in_newline \$libs \$ldflags"
   }
   tool("stamp") {
     command = "$python_path gyp-win-tool stamp \$out"
     description = "STAMP \$out"
   }
   tool("copy") {
     command = "$python_path gyp-win-tool recursive-mirror \$in \$out"
     description = "COPY \$in \$out"
   }
 }
 
 # 64-bit toolchain -------------------------------------------------------------
 
 toolchain("64") {
 }