Add a field trial for using lower sqlite cache sizes.

chrome/browser/history/history_database.cc

 // Copyright (c) 2011 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/history/history_database.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/metrics/histogram.h"
 #include "base/rand_util.h"
 #include "base/string_util.h"
 #include "chrome/browser/diagnostics/sqlite_diagnostics.h"
+#include "chrome/browser/history/history_field_trial.h"
 #include "sql/transaction.h"
 
 #if defined(OS_MACOSX)
 #include "base/mac/mac_util.h"
 #endif
 
 namespace history {
 
 namespace {
 
@@ skipping 44 matching lines @@
                                       const FilePath& bookmarks_path) {
   // Set the exceptional sqlite error handler.
   db_.set_error_delegate(GetErrorHandlerForHistoryDb());
 
   // Set the database page size to something a little larger to give us
   // better performance (we're typically seek rather than bandwidth limited).
   // This only has an effect before any tables have been created, otherwise
   // this is a NOP. Must be a power of 2 and a max of 8192.
   db_.set_page_size(4096);
 
-  // Increase the cache size. The page size, plus a little extra, times this
-  // value, tells us how much memory the cache will use maximum.
-  // 6000 * 4MB = 24MB
-  // TODO(brettw) scale this value to the amount of available memory.
-  db_.set_cache_size(6000);
+  if (HistoryFieldTrial::IsLowMemFieldTrial()) {
+    db_.set_cache_size(500);
+  } else {
+    // Increase the cache size. The page size, plus a little extra, times this
+    // value, tells us how much memory the cache will use maximum.
+    // 6000 * 4MB = 24MB
+    // TODO(brettw) scale this value to the amount of available memory.
+    db_.set_cache_size(6000);
+  }
 
   // Note that we don't set exclusive locking here. That's done by
   // BeginExclusiveMode below which is called later (we have to be in shared
   // mode to start out for the in-memory backend to read the data).
 
   if (!db_.Open(history_name))
     return sql::INIT_FAILURE;
 
   // Wrap the rest of init in a tranaction. This will prevent the database from
   // getting corrupted if we crash in the middle of initialization or migration.
@@ skipping 239 matching lines @@
       "WHERE id IN (SELECT id FROM segment_usage WHERE time_slot > 0);");
 
   // Erase all the full text index files. These will take a while to update and
   // are less important, so we just blow them away. Same with the archived
   // database.
   needs_version_17_migration_ = true;
 }
 #endif
 
 }  // namespace history