Reduce the HistoryDatabase's page cache from 6000 (24MB) to 1000 (4MB) pages.

Shrinking the history databases page cache doesn't seem to impact performance
of the QueryHistory time metric, or the page cycler.

BUG=243769

Review URL: https://chromiumcodereview.appspot.com/17416002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@208036 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/history/history_database.cc

@@ -56,11 +56,11 @@ sql::InitStatus HistoryDatabase::Init(const base::FilePath& history_name) {
   // 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
+  // Set 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
+  // 1000 * 4kB = 4MB
   // TODO(brettw) scale this value to the amount of available memory.
-  db_.set_cache_size(6000);
+  db_.set_cache_size(1000);
 
   // 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