AppCache: Run a quick integrity check on the sqlite database when opening.

sql/connection.h

Index: sql/connection.h
diff --git a/sql/connection.h b/sql/connection.h
index ec76e3be89a133075f287cfb917cdd2c5ba91e30..54c3f8b7b8e672cf50749dc4c4673eb0cae99bfb 100644
--- a/sql/connection.h
+++ b/sql/connection.h
@@ -150,11 +150,16 @@ class SQL_EXPORT Connection {
   // histogram is recorded.
   void AddTaggedHistogram(const std::string& name, size_t sample) const;
 
-  // Run "PRAGMA integrity_check" and post each line of results into
-  // |messages|.  Returns the success of running the statement - per
-  // the SQLite documentation, if no errors are found the call should
-  // succeed, and a single value "ok" should be in messages.
-  bool IntegrityCheck(std::vector<std::string>* messages);
+  // Run "PRAGMA integrity_check" and post each line of
+  // results into |messages|.  Returns the success of running the
+  // statement - per the SQLite documentation, if no errors are found the
+  // call should succeed, and a single value "ok" should be in messages.
+  bool FullIntegrityCheck(std::vector<std::string>* messages);
+
+  // Runs "PRAGMA quick_check" and, unlike the FullIntegrityCheck method,
+  // interprets the results returning true if the the statement executes
+  // without error and results in a single "ok" value.
+  bool QuickIntegrityCheck() WARN_UNUSED_RESULT;
 
   // Initialization ------------------------------------------------------------
 
@@ -540,6 +545,10 @@ class SQL_EXPORT Connection {
   // case for const functions).
   scoped_refptr<StatementRef> GetUntrackedStatement(const char* sql) const;
 
+  bool IntegrityCheckHelper(
+      const char* pragma_sql,
+      std::vector<std::string>* messages) WARN_UNUSED_RESULT;
+
   // The actual sqlite database. Will be NULL before Init has been called or if
   // Init resulted in an error.
   sqlite3* db_;