Add flac into root BUILD.gn

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git
 #   gclient runhooks
 # DO NOT CHECK IN CHANGES TO .DEPS.git. It will be automatically updated by
 # a bot when you modify this one.
@@ skipping 211 matching lines @@
   "src/third_party/speex":
     "/trunk/deps/third_party/speex@198168",
 
   "src/third_party/yasm/source/patched-yasm":
     "/trunk/deps/third_party/yasm/patched-yasm@167605",
 
   "src/third_party/libjpeg_turbo":
     "/trunk/deps/third_party/libjpeg_turbo@263594",
 
   "src/third_party/flac":
-    "/trunk/deps/third_party/flac@222897",
+    "/trunk/deps/third_party/flac@266977",
 
   "src/third_party/pyftpdlib/src":
     (Var("googlecode_url") % "pyftpdlib") + "/trunk@977",
 
   "src/third_party/scons-2.0.1":
     Var("nacl_trunk") + "/src/third_party/scons-2.0.1@" +
         Var("nacl_tools_revision"),
 
   "src/third_party/webrtc":
     (Var("googlecode_url") % "webrtc") + "/trunk/webrtc@" + Var("webrtc_revision"),
@@ skipping 512 matching lines @@
                 "-s", "src/build/linux/bin/eu-strip.sha1",
     ],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "name": "gyp",
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
 ]