[GN] Add solink_module tool on the Mac, Win, and GCC toolchains.

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.
 
 declare_args() {
   # Path to the directory containing the VC binaries for the right
   # combination of host and target architectures. Currently only the
   # 64-bit host toolchain is supported, with either 32-bit or 64-bit targets.
   # If vc_bin_dir is not specified on the command line (and it normally
   # isn't), we will dynamically determine the right value to use at runtime.
@@ skipping 156 matching lines @@
       # Since the above commands only updates the .lib file when it changes, ask
       # Ninja to check if the timestamp actually changed to know if downstream
       # dependencies should be recompiled.
       restat = true
 
       # The use of inputs_newline is to work around a fixed per-line buffer
       # size in the linker.
       rspfile_content = "{{libs}} {{solibs}} {{inputs_newline}} {{ldflags}}"
     }
 
+    tool("solink_module") {
+      dllname = "{{root_out_dir}}/{{target_output_name}}{{output_extension}}"  # e.g. foo.dll
+      rspfile = "${dllname}.rsp"
+
+      link_command = "$python_path gyp-win-tool link-wrapper $env False link.exe /nologo /DLL /OUT:$dllname /PDB:${dllname}.pdb @$rspfile"
+
+      command = link_command
+
+      default_output_extension = ".dll"
+      description = "LINK_MODULE(DLL) {{output}}"
+      outputs = [
+        dllname,
+      ]
+
+      # The use of inputs_newline is to work around a fixed per-line buffer
+      # size in the linker.
+      rspfile_content = "{{libs}} {{solibs}} {{inputs_newline}} {{ldflags}}"
+    }
+
     tool("link") {
       rspfile = "{{output}}.rsp"
 
       link_command = "$python_path gyp-win-tool link-wrapper $env False link.exe /nologo /OUT:{{output}} /PDB:{{output}}.pdb @$rspfile"
 
       # TODO(brettw) support manifests
       #manifest_command = "$python_path gyp-win-tool manifest-wrapper $env mt.exe -nologo -manifest $manifests -out:{{output}}.manifest"
       #command = "cmd /c $link_command && $manifest_command"
       command = link_command
 
@@ skipping 82 matching lines @@
 }
 
 msvc_toolchain("winrt_x64") {
   environment = "environment.winrt_x64"
   cl = "${goma_prefix}\"${vc_bin_dir}/cl.exe\""
   is_clang = false
 
   current_cpu = "x64"
   current_os = current_os
 }