[Extensions Bindings] Check availability of custom API properties

extensions/common/features/feature_provider.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/common/features/feature_provider.h"
 
 #include <map>
 #include <memory>
 
 #include "base/command_line.h"
@@ skipping 122 matching lines @@
     return iter->second.get();
   else
     return nullptr;
 }
 
 Feature* FeatureProvider::GetParent(Feature* feature) const {
   CHECK(feature);
   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
 // means they'll be contiguous in the features_ std::map.
 std::vector<Feature*> FeatureProvider::GetChildren(
     const Feature& parent) const {
   std::string prefix = parent.name() + ".";
   const FeatureMap::const_iterator first_child = features_.lower_bound(prefix);
 
   // All children have names before (parent.name() + ('.'+1)).
@@ skipping 18 matching lines @@
 void FeatureProvider::AddFeature(base::StringPiece name,
                                  std::unique_ptr<Feature> feature) {
   features_[name.as_string()] = std::move(feature);
 }
 
 void FeatureProvider::AddFeature(base::StringPiece name, Feature* feature) {
   features_[name.as_string()] = std::unique_ptr<Feature>(feature);
 }
 
 }  // namespace extensions