cc: Remove all blimp code from cc.

cc/proto/skregion.proto

Index: cc/proto/skregion.proto
diff --git a/cc/proto/skregion.proto b/cc/proto/skregion.proto
deleted file mode 100644
index d45feddf9e2432b23af01d2d52360491fede415e..0000000000000000000000000000000000000000
--- a/cc/proto/skregion.proto
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright 2015 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.
-
-syntax = "proto2";
-
-option optimize_for = LITE_RUNTIME;
-
-package cc.proto;
-
-message SkRegion {
-  enum Op {
-    DIFFERENCE_ = 0;  // On Windows, winuser.h defines DIFFERENCE.
-    INTERSECT = 1;
-    UNION = 2;
-    XOR = 3;
-    REVERSE_DIFFERENCE = 4;
-    REPLACE = 5;
-  }
-}