Windows precompiled header support in GN

build/toolchain/win/BUILD.gn

Index: build/toolchain/win/BUILD.gn
diff --git a/build/toolchain/win/BUILD.gn b/build/toolchain/win/BUILD.gn
index 4936c3d0cfc883641333be7dca2617b5fa3eadab..0236c8e6cc91d8317acff23ee004cdd12ae444f0 100644
--- a/build/toolchain/win/BUILD.gn
+++ b/build/toolchain/win/BUILD.gn
@@ -80,6 +80,9 @@ template("msvc_toolchain") {
 
     tool("cc") {
       rspfile = "{{output}}.rsp"
+
+      # TODO(brettw) enable this when GN support in the binary has been rolled.
+      #precompiled_header_type = "msvc"
       pdbname = "{{target_out_dir}}/{{target_output_name}}_c.pdb"
       command = "ninja -t msvc -e $env -- $cl /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}} /Fd$pdbname"
       depsformat = "msvc"
@@ -93,6 +96,9 @@ template("msvc_toolchain") {
     tool("cxx") {
       rspfile = "{{output}}.rsp"
 
+      # TODO(brettw) enable this when GN support in the binary has been rolled.
+      #precompiled_header_type = "msvc"
+
       # The PDB name needs to be different between C and C++ compiled files.
       pdbname = "{{target_out_dir}}/{{target_output_name}}_cc.pdb"
       command = "ninja -t msvc -e $env -- $cl /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}} /Fd$pdbname"