Fix several problems with the content verification code

extensions/browser/content_hash_fetcher.h

 // Copyright 2014 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.
 
 #ifndef EXTENSIONS_BROWSER_CONTENT_HASH_FETCHER_H_
 #define EXTENSIONS_BROWSER_CONTENT_HASH_FETCHER_H_
 
+#include <set>
+#include <string>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
 #include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.h"
 #include "extensions/browser/content_verifier_delegate.h"
 #include "extensions/browser/extension_registry_observer.h"
 #include "extensions/common/extension.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
 class ExtensionRegistry;
 class ContentHashFetcherJob;
 
 // This class is responsible for getting signed expected hashes for use in
 // extension content verification. As extensions are loaded it will fetch and
 // parse/validate/cache this data as needed, including calculating expected
 // hashes for each block of each file within an extension. (These unsigned leaf
 // node block level hashes will always be checked at time of use use to make
 // sure they match the signed treehash root hash).
 class ContentHashFetcher : public ExtensionRegistryObserver {
  public:
+  // A callback for when a fetch is complete. This reports back:
+  // -extension id
+  // -whether we were successful or not (have verified_contents.json and
+  // -computed_hashes.json files)
+  // -was it a forced check?
+  // -a set of paths whose contents didn't match expected values
+  typedef base::Callback<
+      void(const std::string&, bool, bool, const std::set<base::FilePath>&)>
+      FetchCallback;
+
   // The consumer of this class needs to ensure that context and delegate
   // outlive this object.
   ContentHashFetcher(content::BrowserContext* context,
-                     ContentVerifierDelegate* delegate);
+                     ContentVerifierDelegate* delegate,
+                     const FetchCallback& callback);
   virtual ~ContentHashFetcher();
 
   // Begins the process of trying to fetch any needed verified contents, and
   // listening for extension load/unload.
   void Start();
 
-  // Explicitly ask to fetch hashes for |extension|.
-  void DoFetch(const Extension* extension);
+  // Explicitly ask to fetch hashes for |extension|. If |force| is true,
+  // we will always check the validity of the verified_contents.json and
+  // re-check the contents of the files in the filesystem.
+  void DoFetch(const Extension* extension, bool force);
 
   // ExtensionRegistryObserver interface
   virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
                                  const Extension* extension) OVERRIDE;
   virtual void OnExtensionUnloaded(
       content::BrowserContext* browser_context,
       const Extension* extension,
       UnloadedExtensionInfo::Reason reason) OVERRIDE;
 
  private:
   // Callback for when a job getting content hashes has completed.
   void JobFinished(ContentHashFetcherJob* job);
 
   content::BrowserContext* context_;
   ContentVerifierDelegate* delegate_;
+  FetchCallback fetch_callback_;
 
   // We keep around pointers to in-progress jobs, both so we can avoid
   // scheduling duplicate work if fetching is already in progress, and so that
   // we can cancel in-progress work at shutdown time.
   typedef std::pair<ExtensionId, std::string> IdAndVersion;
   typedef std::map<IdAndVersion, scoped_refptr<ContentHashFetcherJob> > JobMap;
   JobMap jobs_;
 
   // For observing the ExtensionRegistry.
   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver> observer_;
 
   // Used for binding callbacks passed to jobs.
   base::WeakPtrFactory<ContentHashFetcher> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentHashFetcher);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_CONTENT_HASH_FETCHER_H_