XXX test gn format everything

tools/gn/example/build/toolchain/BUILD.gn

 # Copyright 2014 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.
 
 toolchain("gcc") {
   tool("cc") {
     depfile = "{{output}}.d"
-    command = "gcc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
+    command =
+        "gcc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
     depsformat = "gcc"
     description = "CC {{output}}"
-    outputs = [
-      "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o",
-    ]
+    outputs =
+        [ "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o" ]
   }
 
   tool("cxx") {
     depfile = "{{output}}.d"
-    command = "g++ -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
+    command =
+        "g++ -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
     depsformat = "gcc"
     description = "CXX {{output}}"
-    outputs = [
-      "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o",
-    ]
+    outputs =
+        [ "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o" ]
   }
 
   tool("alink") {
     rspfile = "{{output}}.rsp"
     command = "rm -f {{output}} && ar rcs {{output}} @$rspfile"
     description = "AR {{target_output_name}}{{output_extension}}"
     rspfile_content = "{{inputs}}"
-    outputs = [
-      "{{target_out_dir}}/{{target_output_name}}{{output_extension}}"
-    ]
+    outputs =
+        [ "{{target_out_dir}}/{{target_output_name}}{{output_extension}}" ]
     default_output_extension = ".a"
     output_prefix = "lib"
   }
 
   tool("solink") {
     soname = "{{target_output_name}}{{output_extension}}"  # e.g. "libfoo.so".
     rspfile = soname + ".rsp"
 
     command = "g++ -shared {{ldflags}} -o $soname -Wl,-soname=$soname @$rspfile"
-    rspfile_content = "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive {{libs}}"
+    rspfile_content =
+        "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive {{libs}}"
 
     description = "SOLINK $soname"
 
     # Use this for {{output_extension}} expansions unless a target manually
     # overrides it (in which case {{output_extension}} will be what the target
     # specifies).
     default_output_extension = ".so"
 
-    outputs = [
-      soname,
-    ]
+    outputs = [ soname ]
     link_output = soname
     depend_output = soname
     output_prefix = "lib"
   }
 
   tool("link") {
     outfile = "{{target_output_name}}{{output_extension}}"
     rspfile = "$outfile.rsp"
-    command = "g++ {{ldflags}} -o $outfile -Wl,--start-group @$rspfile {{solibs}} -Wl,--end-group {{libs}}"
+    command =
+        "g++ {{ldflags}} -o $outfile -Wl,--start-group @$rspfile {{solibs}} -Wl,--end-group {{libs}}"
     description = "LINK $outfile"
     rspfile_content = "{{inputs}}"
     outputs = [ outfile ]
   }
 
   tool("stamp") {
     command = "touch {{output}}"
     description = "STAMP {{output}}"
   }
 
   tool("copy") {
     command = "cp -af {{source}} {{output}}"
     description = "COPY {{source}} {{output}}"
   }
 }