Simplify SkBBH::insert API

No one's exploiting the ability to take ownership of the array anymore.

BUG=skia:

Review URL: https://codereview.chromium.org/913833002
diff --git a/tests/RTreeTest.cpp b/tests/RTreeTest.cpp
index 50eaacb..16ccb4f 100644
--- a/tests/RTreeTest.cpp
+++ b/tests/RTreeTest.cpp
@@ -80,7 +80,7 @@
             rects[j] = random_rect(rand);
         }
 
-        rtree.insert(&rects, NUM_RECTS);
+        rtree.insert(rects.get(), NUM_RECTS);
         SkASSERT(rects);  // SkRTree doesn't take ownership of rects.
 
         run_queries(reporter, rand, rects, rtree);