Pull in Mesa to src/third_party/mesa/src via DEPS.

DEPS

 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 
 vars = {
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   "googlecode_url": "http://%s.googlecode.com/svn",
   "sourceforge_url": "http://%(repo)s.svn.sourceforge.net/svnroot/%(repo)s",
   "webkit_trunk": "http://src.chromium.org/blink/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
@@ skipping 299 matching lines @@
     (Var("googlecode_url") % "pywebsocket") + "/trunk/src@662",
 
   "src/third_party/opus/src":
     "/trunk/deps/third_party/opus@185324",
 
   "src/third_party/accessibility-developer-tools":
     Var("chromium_git") + "/external/accessibility-developer-tools.git@ad5df9a5341d38778658c90e4aa241c4ebe4e8aa",
 
   "src/webkit/renderer/media/crypto/ppapi/cdm":
     "/trunk/deps/cdm@181763",
+
+  "src/third_party/mesa/src":
+    "/trunk/deps/third_party/mesa@204346",
 }
 
 
 deps_os = {
   "win": {
     "src/chrome/tools/test/reference_build/chrome_win":
       "/trunk/deps/reference_builds/chrome_win@197743",
 
     "src/third_party/cygwin":
       "/trunk/deps/third_party/cygwin@133786",
@@ skipping 343 matching lines @@
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
   {
     # Check for landmines (reasons to clobber the build).
     "pattern": ".",
     "action": ["python", "src/build/landmines.py"],
   },
 ]