Make Spawns runfiles aware

Introduce RunfilesSupplier for carrying runfiles all the way to the
execution related bits without expanding them/to deal with package
visibility.

--
MOS_MIGRATED_REVID=93540344

src/main/java/com/google/devtools/build/lib/analysis/RunfilesSupplierImpl.java

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RunfilesSupplierImpl.java b/src/main/java/com/google/devtools/build/lib/analysis/RunfilesSupplierImpl.java
new file mode 100644
index 0000000..cfb84c2
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RunfilesSupplierImpl.java
@@ -0,0 +1,65 @@
+// Copyright 2015 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.analysis;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.actions.RunfilesSupplier;
+import com.google.devtools.build.lib.vfs.PathFragment;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Map.Entry;
+
+/**
+ * {@link RunfilesSupplier} implementation wrapping directory to {@link Runfiles} objects mappings.
+ */
+public class RunfilesSupplierImpl implements RunfilesSupplier {
+
+  private final ImmutableMap<PathFragment, Runfiles> inputRunfiles;
+
+  /**
+   * Create an instance when you have a a single mapping.
+   *
+   * @param runfilesDir the desired runfiles directory. Should be relative.
+   * @param runfiles the runfiles for runfilesDir
+   */
+  public RunfilesSupplierImpl(PathFragment runfilesDir, Runfiles runfiles) {
+    this.inputRunfiles = ImmutableMap.of(runfilesDir, runfiles);
+  }
+
+  @VisibleForTesting
+  public RunfilesSupplierImpl(Map<PathFragment, Runfiles> inputRunfiles) {
+    this.inputRunfiles = ImmutableMap.copyOf(inputRunfiles);
+  }
+
+  @Override
+  public ImmutableSet<PathFragment> getRunfilesDirs() {
+    return inputRunfiles.keySet();
+  }
+
+  @Override
+  public ImmutableMap<PathFragment, Map<PathFragment, Artifact>> getMappings() throws IOException {
+    ImmutableMap.Builder<PathFragment, Map<PathFragment, Artifact>> result =
+        ImmutableMap.builder();
+    for (Entry<PathFragment, Runfiles> entry : inputRunfiles.entrySet()) {
+      result.put(entry.getKey(), entry.getValue().getRunfilesInputs(null, null));
+    }
+    return result.build();
+  }
+
+}