Make goma work on win GN builds.

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 87bd254ca8303b4a04e3cb59965ec34e1b9fa2a2..e9c52ca1e4c4530aa608bb63e50f28aee973589d 100644
--- a/build/toolchain/win/BUILD.gn
+++ b/build/toolchain/win/BUILD.gn
@@ -46,15 +46,34 @@ template("msvc_toolchain") {
                                         configuration,
                                         invoker.cpu_arch])
 
+  if (use_goma) {
+    goma_prefix = "$goma_dir/gomacc.exe "
+  } else {
+    goma_prefix = ""
+  }
+
+  if (cpu_arch == "x86") {
+    vc_bin = "\vc\bin\amd64_x86"
+  } else {
+    vc_bin = "\vc\bin\amd64"
+  }

[Dirk Pranke, 2014/11/20 03:47:13]

Scott: is there a better way to get the right subdir here? It seems like
visual_studio_version.gni doesn't actual ly set this up, but perhaps it (and
vs_toolchain.py) should?

[scottmg, 2014/11/20 04:58:34]

Yes, setup_toolchain should probably do the same as gyp does in
https://code.google.com/p/chromium/codesearch#chromium/src/tools/gyp/pylib/gy...
and return it in vs_toolchain via GetToolchainDir()

[Dirk Pranke, 2014/11/20 05:01:03]

Okay, will fix.

+  cl = "${goma_prefix}\"${visual_studio_path}${vc_bin}/cl.exe\""
+
   toolchain(target_name) {
     # Make these apply to all tools below.
     lib_switch = ""
     lib_dir_switch="/LIBPATH:"
 
     tool("cc") {
+      if (use_goma) {

[scottmg, 2014/11/20 04:58:34]

you could probably just leave this to avoid the conditional, I don't think it'll
matter if it's there.

[Dirk Pranke, 2014/11/20 05:01:03]

Okay, I'll doublecheck to make sure and always pass the pdb if it works.

+        pdb_flag = ""
+      } else {
+        pdb_flag = " /Fd{{target_out_dir}}/{{target_output_name}}_c.pdb"
+      }
+
       rspfile = "{{output}}.rsp"
-      pdbname = "{{target_out_dir}}/{{target_output_name}}_c.pdb"
-      command = "ninja -t msvc -e $env -- cl.exe /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}} /Fd$pdbname"
+      command = "ninja -t msvc -e $env -- $cl /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}}$pdb_flag"
+
       depsformat = "msvc"
       description = "CC {{output}}"
       outputs = [
@@ -64,10 +83,15 @@ template("msvc_toolchain") {
     }
 
     tool("cxx") {
+      if (use_goma) {

[scottmg, 2014/11/20 04:58:34]

same

[Dirk Pranke, 2014/11/20 05:01:03]

Acknowledged.

+        pdb_flag = ""
+      } else {
+        # The PDB name needs to be different between C and C++ compiled files.
+        pdb_flag = " /Fd{{target_out_dir}}/{{target_output_name}}_cc.pdb"
+      }
+
       rspfile = "{{output}}.rsp"
-      # 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 $env -- cl.exe /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}} /Fd$pdbname"
+      command = "ninja -t msvc -e $env -- $cl /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}}$pdb_flag"
       depsformat = "msvc"
       description = "CXX {{output}}"
       outputs = [