[Content verification] Fix a bug for files that are multiple of 4k bytes.

extensions/browser/content_verify_job.cc

 // 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.
 
 #include "extensions/browser/content_verify_job.h"
 
 #include <algorithm>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
@@ skipping 124 matching lines @@
     if (!FinishBlock()) {
       DispatchFailureCallback(HASH_MISMATCH);
     } else if (g_test_observer) {
       g_test_observer->JobFinished(hash_reader_->extension_id(),
                                    hash_reader_->relative_path(), NONE);
     }
   }
 }
 
 bool ContentVerifyJob::FinishBlock() {
-  if (!done_reading_ && current_hash_byte_count_ == 0)
-    return true;
+  if (current_hash_byte_count_ == 0) {
+    if (!done_reading_ ||
+        // If we have checked all blocks already, then nothing else to do here.
+        current_block_ == hash_reader_->block_count()) {
+      return true;
+    }
+  }
   if (!current_hash_) {
     // This happens when we fail to read the resource. Compute empty content's
     // hash in this case.
     current_hash_ = crypto::SecureHash::Create(crypto::SecureHash::SHA256);
   }
   std::string final(crypto::kSHA256Length, 0);
   current_hash_->Finish(base::string_as_array(& final), final.size());
   current_hash_.reset();
   current_hash_byte_count_ = 0;
 
@@ skipping 70 matching lines @@
             << " reason:" << reason;
     std::move(failure_callback_).Run(reason);
   }
   if (g_test_observer) {
     g_test_observer->JobFinished(hash_reader_->extension_id(),
                                  hash_reader_->relative_path(), reason);
   }
 }
 
 }  // namespace extensions