Remove some very old-file-format code from safe browsing store.

chrome/browser/safe_browsing/safe_browsing_store_file.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.
 
 #include "chrome/browser/safe_browsing/safe_browsing_store_file.h"
 
 #include "base/file_util.h"
 #include "base/files/scoped_file.h"
 #include "base/md5.h"
 #include "base/metrics/histogram.h"
@@ skipping 68 matching lines @@
 
 // Enumerate different format-change events for histogramming
 // purposes.  DO NOT CHANGE THE ORDERING OF THESE VALUES.
 enum FormatEventType {
   // Corruption detected, broken down by file format.
   FORMAT_EVENT_FILE_CORRUPT,
   FORMAT_EVENT_SQLITE_CORRUPT,  // Obsolete
 
   // The type of format found in the file.  The expected case (new
   // file format) is intentionally not covered.
-  FORMAT_EVENT_FOUND_SQLITE,
-  FORMAT_EVENT_FOUND_UNKNOWN,
+  FORMAT_EVENT_FOUND_SQLITE,  // Obsolete
+  FORMAT_EVENT_FOUND_UNKNOWN,  // magic does not match.
 
   // The number of SQLite-format files deleted should be the same as
   // FORMAT_EVENT_FOUND_SQLITE.  It can differ if the delete fails,
   // or if a failure prevents the update from succeeding.
   FORMAT_EVENT_SQLITE_DELETED,  // Obsolete
   FORMAT_EVENT_SQLITE_DELETE_FAILED,  // Obsolete
 
   // Found and deleted (or failed to delete) the ancient "Safe
   // Browsing" file.
-  FORMAT_EVENT_DELETED_ORIGINAL,
-  FORMAT_EVENT_DELETED_ORIGINAL_FAILED,
+  FORMAT_EVENT_DELETED_ORIGINAL,  // Obsolete
+  FORMAT_EVENT_DELETED_ORIGINAL_FAILED,  // Obsolete
 
   // The checksum did not check out in CheckValidity() or in
   // FinishUpdate().  This most likely indicates that the machine
   // crashed before the file was fully sync'ed to disk.
   FORMAT_EVENT_VALIDITY_CHECKSUM_FAILURE,
   FORMAT_EVENT_UPDATE_CHECKSUM_FAILURE,
 
   // The header checksum was incorrect in ReadAndVerifyHeader().  Likely
   // indicates that the system crashed while writing an update.
   FORMAT_EVENT_HEADER_CHECKSUM_FAILURE,
 
+  FORMAT_EVENT_FOUND_DEPRECATED,  // version too old.
+
   // Memory space for histograms is determined by the max.  ALWAYS
   // ADD NEW VALUES BEFORE THIS ONE.
   FORMAT_EVENT_MAX
 };
 
 void RecordFormatEvent(FormatEventType event_type) {
   UMA_HISTOGRAM_ENUMERATION("SB2.FormatEvent", event_type, FORMAT_EVENT_MAX);
 }
 
 // Rewind the file.  Using fseek(2) because rewind(3) errors are
@@ skipping 500 matching lines @@
 
   int64 size = 0;
   if (!base::GetFileSize(filename, &size))
     return false;
 
   return static_cast<int64>(ftell(file.get())) == size;
 }
 
 }  // namespace
 
-// static
-void SafeBrowsingStoreFile::CheckForOriginalAndDelete(
-    const base::FilePath& current_filename) {
-  const base::FilePath original_filename(
-      current_filename.DirName().AppendASCII("Safe Browsing"));
-  if (base::PathExists(original_filename)) {
-    int64 size = 0;
-    if (base::GetFileSize(original_filename, &size)) {
-      UMA_HISTOGRAM_COUNTS("SB2.OldDatabaseKilobytes",

[Alexei Svitkine (slow), 2014/07/23 14:41:16]

Can you mark this histogram with an <obsolete> tag in histograms.xml?

[Scott Hess - ex-Googler, 2014/07/23 17:18:19]

Done.

-                           static_cast<int>(size / 1024));
-    }
-
-    if (base::DeleteFile(original_filename, false)) {
-      RecordFormatEvent(FORMAT_EVENT_DELETED_ORIGINAL);
-    } else {
-      RecordFormatEvent(FORMAT_EVENT_DELETED_ORIGINAL_FAILED);
-    }
-
-    // Just best-effort on the journal file, don't want to get lost in
-    // the weeds.
-    const base::FilePath journal_filename(
-        current_filename.DirName().AppendASCII("Safe Browsing-journal"));
-    base::DeleteFile(journal_filename, false);
-  }
-}
-
 SafeBrowsingStoreFile::SafeBrowsingStoreFile()
     : chunks_written_(0), empty_(false), corruption_seen_(false) {}
 
 SafeBrowsingStoreFile::~SafeBrowsingStoreFile() {
   Close();
 }
 
 bool SafeBrowsingStoreFile::Delete() {
   // The database should not be open at this point.  But, just in
   // case, close everything before deleting.
@@ skipping 141 matching lines @@
   DCHECK(add_chunks_cache_.empty());
   DCHECK(sub_chunks_cache_.empty());
   DCHECK(add_del_cache_.empty());
   DCHECK(sub_del_cache_.empty());
   DCHECK(add_prefixes_.empty());
   DCHECK(sub_prefixes_.empty());
   DCHECK(add_hashes_.empty());
   DCHECK(sub_hashes_.empty());
   DCHECK_EQ(chunks_written_, 0);
 
-  // Since the following code will already hit the profile looking for
-  // database files, this is a reasonable to time delete any old
-  // files.
-  CheckForOriginalAndDelete(filename_);
-
   corruption_seen_ = false;
 
   const base::FilePath new_filename = TemporaryFileForFilename(filename_);
   base::ScopedFILE new_file(base::OpenFile(new_filename, "wb+"));
   if (new_file.get() == NULL)
     return false;
 
   base::ScopedFILE file(base::OpenFile(filename_, "rb"));
   empty_ = (file.get() == NULL);
   if (empty_) {
     // If the file exists but cannot be opened, try to delete it (not
     // deleting directly, the bloom filter needs to be deleted, too).
     if (base::PathExists(filename_))
       return OnCorruptDatabase();
 
     new_file_.swap(new_file);
     return true;
   }
 
   base::MD5Context context;
   FileHeader header;
   const int version =
       ReadAndVerifyHeader(filename_, &header,
                           &add_chunks_cache_, &sub_chunks_cache_,
                           file.get(), &context);
   if (version == kInvalidVersion) {
     FileHeaderV8 retry_header;
-    if (FileRewind(file.get()) && ReadItem(&retry_header, file.get(), NULL) &&
-        (retry_header.magic != kFileMagic ||
-         (retry_header.version != 8 && retry_header.version != 7))) {
-      // TODO(shess): Think on whether these histograms are generating any
-      // actionable data.  I kid you not, SQLITE happens many thousands of times
-      // per day, UNKNOWN about 3x higher than that.
-      if (!strcmp(reinterpret_cast<char*>(&retry_header.magic),
-                  "SQLite format 3")) {
-        RecordFormatEvent(FORMAT_EVENT_FOUND_SQLITE);
+    if (FileRewind(file.get()) && ReadItem(&retry_header, file.get(), NULL)) {
+      if (retry_header.magic == kFileMagic && retry_header.version < 7) {
+        RecordFormatEvent(FORMAT_EVENT_FOUND_DEPRECATED);
       } else {
         RecordFormatEvent(FORMAT_EVENT_FOUND_UNKNOWN);
       }
     }
 
     // Close the file so that it can be deleted.
     file.reset();
 
     return OnCorruptDatabase();
   }
@@ skipping 372 matching lines @@
   // With SQLite support gone, one way to get to this code is if the
   // existing file is a SQLite file.  Make sure the journal file is
   // also removed.
   const base::FilePath journal_filename(
       basename.value() + FILE_PATH_LITERAL("-journal"));
   if (base::PathExists(journal_filename))
     base::DeleteFile(journal_filename, false);
 
   return true;
 }