Make skydb --gdb work on mac.

sky/tools/skydb

 #!/usr/bin/env python
 # 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.
 
 from skypy.skyserver import SkyServer
 import argparse
 import json
 import logging
 import os
 import pipes
 import re
 import requests
 import signal
 import skypy.paths
 import StringIO
 import subprocess
 import sys
 import time
 import urlparse
+import platform
 
 SUPPORTED_MIME_TYPES = [
     'text/html',
     'text/sky',
     'text/plain',
 ]
 
 DEFAULT_SKY_COMMAND_PORT = 7777
 GDB_PORT = 8888
 SKY_SERVER_PORT = 9999
@@ skipping 493 matching lines @@
         if 'remote_sky_server_port' in self.pids:
             self._add_android_library_links(CACHE_LINKS_PATH)
 
             system_lib_dirs = self._pull_system_libraries(SYSTEM_LIBS_ROOT_PATH)
             eval_commands.append(
                 'set solib-absolute-prefix %s' % SYSTEM_LIBS_ROOT_PATH)
 
             symbol_search_paths = system_lib_dirs + symbol_search_paths
 
             # TODO(eseidel): We need to look up the toolchain somehow?
-            gdb_path = os.path.join(SRC_ROOT, 'third_party/android_tools/ndk/'
-                'toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/'
-                'bin/arm-linux-androideabi-gdb')
+            if platform.system() == 'Darwin':
+                gdb_path = os.path.join(SRC_ROOT, 'third_party/android_tools/ndk/'
+                    'toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/'
+                    'bin/arm-linux-androideabi-gdb')
+            else:
+                gdb_path = os.path.join(SRC_ROOT, 'third_party/android_tools/ndk/'
+                    'toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/'
+                    'bin/arm-linux-androideabi-gdb')
 
         # Set solib-search-path after letting android modify symbol_search_paths
         eval_commands.append(
             'set solib-search-path %s' % ':'.join(symbol_search_paths))
 
         exec_command = [gdb_path]
         for command in eval_commands:
             exec_command += ['--eval-command', command]
 
         print " ".join(exec_command)
@@ skipping 83 matching lines @@
         load_parser.set_defaults(func=self.load_command)
 
         args = parser.parse_args()
         args.func(args)
 
         self._write_pid_file(PID_FILE_PATH, self.pids)
 
 
 if __name__ == '__main__':
     SkyDebugger().main()