Introduce apple_watch2_extension rule for bundling watchOS2 extensions.

This can be used in conjunction with apple_binary to add watchOS2 extensions to an ios application bundle.

This is the majority of the native work for this bundling logic. Before announcing general availability of this feature, we will want to:
1. Iterate with teams who have existing watchOS2 apps to catch any corner-case bugs
2. Introduce a skylark macro to wrap apple_watch2_extension and apple_binary into a single rule; this will both serve as a convenience and ensure users set the appropriate linkopts and platformtype on their apple_binary target.

--
MOS_MIGRATED_REVID=129122855

1 files changed, 9 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
index 0ccc9d2752..455526a393 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
@@ -86,6 +86,15 @@ public final class IntermediateArtifacts {
   }
 
   /**
+   * Returns the location of this target's extension plist which contains entries required by all
+   * watch extensions (for final merging into the bundle plist).
+   */
+  public Artifact watchExtensionAutomaticPlist() {
+    return ruleContext.getRelatedArtifact(
+        ruleContext.getUniqueDirectory("plists"), "-automatic-watchExtensionInfo.plist");
+  }
+
+  /**
    * Returns a derived artifact in the bin directory obtained by appending some extension to the end
    * of the given {@link PathFragment}.
    */