Fix content verification code for undreadable and deleted files.

extensions/browser/content_hash_reader.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_READER_H_
 #define EXTENSIONS_BROWSER_CONTENT_HASH_READER_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 21 matching lines @@
 
   const std::string& extension_id() const { return extension_id_; }
   const base::FilePath& relative_path() const { return relative_path_; }
 
   // This should be called to initialize this object (reads the expected hashes
   // from storage, etc.). Must be called on a thread that is allowed to do file
   // I/O. Returns a boolean indicating success/failure. On failure, this object
   // should likely be discarded.
   bool Init();
 
-  // Indicates whether the content in question exists in the local extension
-  // installation. This may be |false| if Init fails.
-  bool content_exists() const { return content_exists_; }
-
   // These return whether we found valid verified_contents.json /
   // computed_hashes.json files respectively. Note that both of these can be
   // true but we still didn't find an entry for |relative_path_| in them.
   bool have_verified_contents() const { return have_verified_contents_; }
   bool have_computed_hashes() const { return have_computed_hashes_; }
+  // Returns whether or not this resource's entry exists in
+  // verified_contents.json (given that both |have_verified_contents_| and
+  // |have_computed_hashes_| are true).
+  bool file_missing_from_verified_contents() const {
+    return file_missing_from_verified_contents_;
+  }
 
   // Return the number of blocks and block size, respectively. Only valid after
   // calling Init().
   int block_count() const;
   int block_size() const;
 
   // Returns a pointer to the expected sha256 hash value for the block at the
   // given index. Only valid after calling Init().
   bool GetHashForBlock(int block_index, const std::string** result) const;
 
  private:
   friend class base::RefCountedThreadSafe<ContentHashReader>;
   virtual ~ContentHashReader();
 
   enum InitStatus { NOT_INITIALIZED, SUCCESS, FAILURE };
 
   std::string extension_id_;
   base::Version extension_version_;
   base::FilePath extension_root_;
   base::FilePath relative_path_;
   ContentVerifierKey key_;
 
   InitStatus status_;
 
-  bool content_exists_;
-
   bool have_verified_contents_;
   bool have_computed_hashes_;
+  bool file_missing_from_verified_contents_;
 
   // The blocksize used for generating the hashes.
   int block_size_;
 
   std::vector<std::string> hashes_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentHashReader);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_CONTENT_HASH_READER_H_