[sql] WARN_UNUSED_RESULT on Execute().

chrome/browser/history/visit_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/visit_database.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 44 matching lines @@
   // save space, we do not record those user browsed visits which would be the
   // majority in this table. Only other sources are recorded.
   // Due to the tight relationship between visit_source and visits table, they
   // should be created and dropped at the same time.
   if (!GetDB().DoesTableExist("visit_source")) {
     if (!GetDB().Execute("CREATE TABLE visit_source("
                          "id INTEGER PRIMARY KEY,source INTEGER NOT NULL)"))
         return false;
   }
 
-  // Index over url so we can quickly find visits for a page. This will just
-  // fail if it already exists and we'll ignore it.
-  GetDB().Execute("CREATE INDEX visits_url_index ON visits (url)");
+  // Index over url so we can quickly find visits for a page.
+  if (!GetDB().Execute(
+          "CREATE INDEX IF NOT EXISTS visits_url_index ON visits (url)"))
+    return false;
 
   // Create an index over from visits so that we can efficiently find
-  // referrers and redirects. Ignore failures because it likely already exists.
-  GetDB().Execute("CREATE INDEX visits_from_index ON visits (from_visit)");
+  // referrers and redirects.
+  if (!GetDB().Execute(
+          "CREATE INDEX IF NOT EXISTS visits_from_index ON "
+          "visits (from_visit)"))
+    return false;
 
   // Create an index over time so that we can efficiently find the visits in a
-  // given time range (most history views are time-based). Ignore failures
-  // because it likely already exists.
-  GetDB().Execute("CREATE INDEX visits_time_index ON visits (visit_time)");
+  // given time range (most history views are time-based).
+  if (!GetDB().Execute(
+          "CREATE INDEX IF NOT EXISTS visits_time_index ON "
+          "visits (visit_time)"))
+    return false;
 
   return true;
 }
 
 bool VisitDatabase::DropVisitTable() {
-  GetDB().Execute("DROP TABLE visit_source");
   // This will also drop the indices over the table.
-  return GetDB().Execute("DROP TABLE visits");
+  return
+      GetDB().Execute("DROP TABLE IF EXISTS visit_source") &&
+      GetDB().Execute("DROP TABLE visits");
 }
 
 // Must be in sync with HISTORY_VISIT_ROW_FIELDS.
 // static
 void VisitDatabase::FillVisitRow(sql::Statement& statement, VisitRow* visit) {
   visit->visit_id = statement.ColumnInt64(0);
   visit->url_id = statement.ColumnInt64(1);
   visit->visit_time = base::Time::FromInternalValue(statement.ColumnInt64(2));
   visit->referring_visit = statement.ColumnInt64(3);
   visit->transition = content::PageTransitionFromInt(statement.ColumnInt(4));
@@ skipping 443 matching lines @@
     // Get the source entries out of the query result.
     while (statement.Step()) {
       std::pair<VisitID, VisitSource> source_entry(statement.ColumnInt64(0),
           static_cast<VisitSource>(statement.ColumnInt(1)));
       sources->insert(source_entry);
     }
   }
 }
 
 }  // namespace history