[Downloads] Rework how hashes are calculated for download files.

components/history/content/browser/content_history_backend_db_unittest.cc

 // Copyright (c) 2012 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.
 
 // History unit tests come in two flavors:
 //
 // 1. The more complicated style is that the unit test creates a full history
 //    service. This spawns a background thread for the history backend, and
 //    all communication is asynchronous. This is useful for testing more
 //    complicated things or end-to-end behavior.
@@ skipping 43 matching lines @@
     {"FILE_FAILED", 1},
     {"FILE_ACCESS_DENIED", 2},
     {"FILE_NO_SPACE", 3},
     {"FILE_NAME_TOO_LONG", 5},
     {"FILE_TOO_LARGE", 6},
     {"FILE_VIRUS_INFECTED", 7},
     {"FILE_TRANSIENT_ERROR", 10},
     {"FILE_BLOCKED", 11},
     {"FILE_SECURITY_CHECK_FAILED", 12},
     {"FILE_TOO_SHORT", 13},
+    {"FILE_HASH_MISMATCH", 14},
     {"NETWORK_FAILED", 20},
     {"NETWORK_TIMEOUT", 21},
     {"NETWORK_DISCONNECTED", 22},
     {"NETWORK_SERVER_DOWN", 23},
     {"NETWORK_INVALID_REQUEST", 24},
     {"SERVER_FAILED", 30},
     {"SERVER_NO_RANGE", 31},
     {"SERVER_PRECONDITION", 32},
     {"SERVER_BAD_CONTENT", 33},
     {"SERVER_UNAUTHORIZED", 34},
@@ skipping 49 matching lines @@
     }
 
     EXPECT_TRUE(found)
         << "Error \"" << cur_reason.name << "\" not found in historical list."
         << std::endl
         << "Please add it.";
   }
 }
 }  // namespace
 }  // namespace history