Add a field trial for using lower sqlite cache sizes.

chrome/browser/history/history_backend.cc

Index: chrome/browser/history/history_backend.cc
===================================================================
--- chrome/browser/history/history_backend.cc	(revision 106923)
+++ chrome/browser/history/history_backend.cc	(working copy)
@@ -20,6 +20,7 @@
 #include "base/time.h"
 #include "chrome/browser/autocomplete/history_url_provider.h"
 #include "chrome/browser/bookmarks/bookmark_service.h"
+#include "chrome/browser/history/history_field_trial.h"
 #include "chrome/browser/history/history_notifications.h"
 #include "chrome/browser/history/history_publisher.h"
 #include "chrome/browser/history/in_memory_history_backend.h"
@@ -374,6 +375,8 @@
   if (!db_.get())
     return;
 
+  TimeTicks beginning_time = TimeTicks::Now();
+
   // Will be filled with the URL ID and the visit ID of the last addition.
   std::pair<URLID, VisitID> last_ids(0, tracker_.GetLastVisit(
       request->id_scope, request->page_id, request->referrer));
@@ -545,6 +548,10 @@
   }
 
   ScheduleCommit();
+
+  UMA_HISTOGRAM_TIMES(
+      "History.AddPage" + HistoryFieldTrial::GetGroupSuffix(),
+      TimeTicks::Now() - beginning_time);
 }
 
 void HistoryBackend::InitImpl(const std::string& languages) {
@@ -554,6 +561,8 @@
   // we only set db_ to the created database if creation is successful. That
   // way other methods won't do anything as db_ is still NULL.
 
+  HistoryFieldTrial::Activate();
+
   TimeTicks beginning_time = TimeTicks::Now();
 
   // Compute the file names. Note that the index file can be removed when the
@@ -1223,8 +1232,9 @@
 
   request->ForwardResult(request->handle(), &request->value);
 
-  UMA_HISTOGRAM_TIMES("History.QueryHistory",
-                      TimeTicks::Now() - beginning_time);
+  UMA_HISTOGRAM_TIMES(
+      "History.QueryHistory" + HistoryFieldTrial::GetGroupSuffix(),
+      TimeTicks::Now() - beginning_time);
 }
 
 // Basic time-based querying of history.