Optimize ExtensionAPI::IsAnyFeatureAvailableToContext from O(#features) to O(#children + log #features).

This also replaces O(N) string allocations with 1 and moves the top-level
feature check to the top of the function to provide a quick exit when the
context has full access.

And it adds an IsAvailable() overload taking a Feature to avoid the string
copies in GetFeatureDependency().

BUG=305000

Review URL: https://codereview.chromium.org/107473004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241706 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 9 insertions, 4 deletions

diff --git a/extensions/common/extension_api.h b/extensions/common/extension_api.h
index a6b0982..024f594 100644
--- a/extensions/common/extension_api.h
+++ b/extensions/common/extension_api.h
@@ -65,10 +65,15 @@ class ExtensionAPI {
   void RegisterDependencyProvider(const std::string& name,
                                   FeatureProvider* provider);
 
-  // Returns true if the specified API is available. |api_full_name| can be
-  // either a namespace name (like "bookmarks") or a member name (like
-  // "bookmarks.create"). Returns true if the feature and all of its
-  // dependencies are available to the specified context.
+  // Returns true if the specified API is available. Returns true if the feature
+  // and all of its dependencies are available to the specified context.
+  Feature::Availability IsAvailable(const Feature& api,
+                                    const Extension* extension,
+                                    Feature::Context context,
+                                    const GURL& url);
+  // Same as the previous overload, but takes a feature name instead of an
+  // object. |api_full_name| can be either a namespace name (like "bookmarks")
+  // or a member name (like "bookmarks.create").
   Feature::Availability IsAvailable(const std::string& api_full_name,
                                     const Extension* extension,
                                     Feature::Context context,