Fix content verification code for undreadable and deleted files.

extensions/browser/content_verify_job.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_VERIFY_JOB_H_
 #define EXTENSIONS_BROWSER_CONTENT_VERIFY_JOB_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 54 matching lines @@
   // are read. Make sure to call DoneReading so that any final bytes that were
   // read that didn't align exactly on a block size boundary get their hash
   // checked as well.
   void BytesRead(int count, const char* data);
 
   // Call once when finished adding bytes via BytesRead.
   void DoneReading();
 
   class TestDelegate {
    public:
+    virtual ~TestDelegate() {}
+
     // These methods will be called inside BytesRead/DoneReading respectively.
     // If either return something other than NONE, then the failure callback
     // will be dispatched with that reason.
     virtual FailureReason BytesRead(const std::string& extension_id,
                                     int count,
                                     const char* data) = 0;
     virtual FailureReason DoneReading(const std::string& extension_id) = 0;
   };
 
   class TestObserver {
@@ skipping 61 matching lines @@
 
   // For ensuring methods on called on the right thread.
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentVerifyJob);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_CONTENT_VERIFY_JOB_H_