Define angle_revision variable in DEPS.

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 48 matching lines @@
   "jsoncpp_revision": "248",
   "nss_revision": "254867",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
   "swarming_revision": "dd806d645e711260c24bf7a2f061d6db091c3715",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling openssl
   # and whatever else without interference from each other.
   "openssl_revision": "253925",
+  # Three lines of non-changing comments so that
+  # the commit queue can handle CLs rolling ANGLE
+  # and whatever else without interference from each other.
+  "angle_revision": "fa63e947cb3eccf463648d21a05d5002c9b8adfa",
 }
 
 deps = {
   "src/breakpad/src":
     (Var("googlecode_url") % "google-breakpad") + "/trunk/src@1271",
 
   "src/sdch/open-vcdiff":
     (Var("googlecode_url") % "open-vcdiff") + "/trunk@42",
 
   "src/testing/gtest":
     (Var("googlecode_url") % "googletest") + "/trunk@643",
 
   "src/testing/gmock":
     (Var("googlecode_url") % "googlemock") + "/trunk@410",
 
   "src/third_party/angle":
-    Var("chromium_git") +
-    "/angle/angle.git@fa63e947cb3eccf463648d21a05d5002c9b8adfa",
+    Var("chromium_git") + "/angle/angle.git@" + Var("angle_revision"),
 
   "src/third_party/trace-viewer":
     (Var("googlecode_url") % "trace-viewer") + "/trunk@1203",
 
   "src/third_party/WebKit":
     Var("webkit_trunk") + "@" + Var("webkit_revision"),
 
   "src/third_party/WebKit/LayoutTests/w3c/web-platform-tests":
     Var("chromium_git") +
     "/external/w3c/web-platform-tests.git@ac4322a338be82b3d8b722917d6d3d057c0a3f6a",
@@ skipping 615 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"],
   },
 ]