[Mac/GN] Implement dSYM generation and stripping.

build/toolchain/mac/BUILD.gn

Index: build/toolchain/mac/BUILD.gn
diff --git a/build/toolchain/mac/BUILD.gn b/build/toolchain/mac/BUILD.gn
index 82eacab28eba0fb0596b1ec649ae3dc20ee422c0..befb234ba5c3049c88654d712a4b1c33ca756d72 100644
--- a/build/toolchain/mac/BUILD.gn
+++ b/build/toolchain/mac/BUILD.gn
@@ -46,6 +46,9 @@ template("mac_toolchain") {
     cxx = invoker.cxx
     ld = invoker.ld
 
+    linker_driver =
+        rebase_path("//build/toolchain/mac/linker_driver.py", root_build_dir)
+
     # Make these apply to all tools below.
     lib_switch = "-l"
     lib_dir_switch = "-L"
@@ -138,7 +141,7 @@ template("mac_toolchain") {
 
       does_reexport_command = "[ ! -e \"$dylib\" -o ! -e \"$tocname\" ] || otool -l \"$dylib\" | grep -q LC_REEXPORT_DYLIB"
 
-      link_command = "$ld -shared "
+      link_command = "$linker_driver $ld -shared "
       if (is_component_build) {
         link_command += " -Wl,-install_name,@rpath/\"{{target_output_name}}{{output_extension}}\" "
       }
@@ -180,8 +183,7 @@ template("mac_toolchain") {
       sofile = "{{output_dir}}/{{target_output_name}}{{output_extension}}"  # eg "./libfoo.so"
       rspfile = sofile + ".rsp"
 
-      link_command =
-          "$ld -bundle {{ldflags}} -o \"$sofile\" -Wl,-filelist,\"$rspfile\""
+      link_command = "$linker_driver $ld -bundle {{ldflags}} -o \"$sofile\" -Wl,-filelist,\"$rspfile\""
       if (is_component_build) {
         link_command += " -Wl,-install_name,@rpath/{{target_output_name}}{{output_extension}}"
       }
@@ -215,7 +217,7 @@ template("mac_toolchain") {
       # do for command-line arguments. Thus any source names with spaces, or
       # label names with spaces (which GN bases the output paths on) will be
       # corrupted by this process. Don't use spaces for source files or labels.
-      command = "$ld {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{solibs}} {{libs}}"
+      command = "$linker_driver $ld {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{solibs}} {{libs}}"
       description = "LINK $outfile"
       rspfile_content = "{{inputs_newline}}"
       outputs = [