Added execution platform to the ActionExecutionMetadata.

Part of #4128.

Change-Id: Id822d3ae6f8daf7c92a75bd8bd28590d4f625845
PiperOrigin-RevId: 177905460
diff --git a/src/main/java/com/google/devtools/build/lib/actions/BaseSpawn.java b/src/main/java/com/google/devtools/build/lib/actions/BaseSpawn.java
index bc52055..437f4b1 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/BaseSpawn.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/BaseSpawn.java
@@ -17,11 +17,13 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.analysis.platform.PlatformInfo;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 /** Base implementation of a Spawn. */
@@ -147,4 +149,10 @@
   public String getMnemonic() {
     return action.getMnemonic();
   }
+
+  @Override
+  @Nullable
+  public PlatformInfo getExecutionPlatform() {
+    return action.getExecutionPlatform();
+  }
 }