[Extensions Bindings] Check availability of custom API properties

extensions/common/features/feature_provider.cc

Index: extensions/common/features/feature_provider.cc
diff --git a/extensions/common/features/feature_provider.cc b/extensions/common/features/feature_provider.cc
index 5e5b14519e50e55c49f0ed5c6fbbaf2da213a24b..0d2f792a65dfb56a617e18dc90d4a500bd2304d0 100644
--- a/extensions/common/features/feature_provider.cc
+++ b/extensions/common/features/feature_provider.cc
@@ -140,12 +140,17 @@ Feature* FeatureProvider::GetParent(Feature* feature) const {
   if (feature->no_parent())
     return nullptr;
 
-  std::vector<base::StringPiece> split = base::SplitStringPiece(
-      feature->name(), ".", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
-  if (split.size() < 2)
-    return nullptr;
-  split.pop_back();
-  return GetFeature(base::JoinString(split, "."));
+  base::StringPiece name = feature->name();
+  base::StringPiece::size_type pos = base::StringPiece::npos;
+  // Continue searching up the chain, so that foo.child.grandchild has a parent
+  // of foo (even if foo.child isn't explicitly defined).
+  while ((pos = name.rfind('.')) != base::StringPiece::npos) {
+    name = name.substr(0, pos);
+    Feature* feature = GetFeature(name.as_string());
+    if (feature)
+      return feature;
+  }
+  return nullptr;
 }
 
 // Children of a given API are named starting with parent.name()+".", which