Update from Google.

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MOE_MIGRATED_REVID=85702957
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleClassProvider.java b/src/main/java/com/google/devtools/build/lib/packages/RuleClassProvider.java
new file mode 100644
index 0000000..90fdfca
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleClassProvider.java
@@ -0,0 +1,49 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.packages;
+
+import com.google.devtools.build.lib.events.EventHandler;
+import com.google.devtools.build.lib.syntax.SkylarkEnvironment;
+import com.google.devtools.build.lib.syntax.ValidationEnvironment;
+
+import java.util.Map;
+
+/**
+ * The collection of the supported build rules. Provides an Environment for Skylark rule creation.
+ */
+public interface RuleClassProvider {
+  /**
+   * Returns a map from rule names to rule class objects.
+   */
+  Map<String, RuleClass> getRuleClassMap();
+
+  /**
+   * Returns a new Skylark Environment instance for rule creation. Implementations need to be
+   * thread safe.
+   */
+  SkylarkEnvironment createSkylarkRuleClassEnvironment(
+      EventHandler eventHandler, String astFileContentHashCode);
+
+  /**
+   * Returns a validation environment for static analysis of skylark files.
+   * The environment has to contain all built-in functions and objects.
+   */
+  ValidationEnvironment getSkylarkValidationEnvironment();
+
+  /**
+   * Returns the Skylark module to register the native rules with.
+   */
+  Object getNativeModule();
+}