Add basic sqlite error handling to the new sqlite handlers...

app/sql/statement.h

 // Copyright (c) 2009 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.
 
 #ifndef APP_SQL_STATEMENT_H_
 #define APP_SQL_STATEMENT_H_
 
 #include <string>
 #include <vector>
 
 #include "app/sql/connection.h"
 #include "base/basictypes.h"
 #include "base/ref_counted.h"
 
 namespace sql {
 
 // Normal usage:
 //   sql::Statement s = connection_.GetUniqueStatement(...);
 //   if (!s)  // You should check for errors before using the statement.
 //     return false;
 //
 //   s.BindInt(0, a);
 //   if (s.Step())
 //     return s.ColumnString(0);
+//
+// Step() and Run() just return true to signal success. If you want to handle
+// specific errors such as database corruption, install an error handler in
+// in the connection object using set_error_delegate().
 class Statement {
  public:
   // Creates an uninitialized statement. The statement will be invalid until
   // you initialize it via Assign.
   Statement();
 
   Statement(scoped_refptr<Connection::StatementRef> ref);
   ~Statement();
 
   // Initializes this object with the given statement, which may or may not
@@ skipping 68 matching lines @@
   std::string ColumnString(int col) const;
 
   // When reading a blob, you can get a raw pointer to the underlying data,
   // along with the length, or you can just ask us to copy the blob into a
   // vector. Danger! ColumnBlob may return NULL if there is no data!
   int ColumnByteLength(int col) const;
   const void* ColumnBlob(int col) const;
   void ColumnBlobAsVector(int col, std::vector<char>* val) const;
   void ColumnBlobAsVector(int col, std::vector<unsigned char>* val) const;
 
+  // Diagnostics --------------------------------------------------------------
+
+  // Returns the original text of sql statement. Do not keep a pointer to it.
+  const char* GetSQLStatement();
+
  private:
   // This is intended to check for serious errors and report them to the
   // connection object. It takes a sqlite error code, and returns the same
   // code. Currently this function just updates the succeeded flag, but will be
   // enhanced in the future to do the notification.
   int CheckError(int err);
 
   // The actual sqlite statement. This may be unique to us, or it may be cached
   // by the connection, which is why it's refcounted. This pointer is
   // guaranteed non-NULL.
   scoped_refptr<Connection::StatementRef> ref_;
 
   // See Succeeded() for what this holds.
   bool succeeded_;
 
   DISALLOW_COPY_AND_ASSIGN(Statement);
 };
 
 }  // namespace sql
 
 #endif  // APP_SQL_STATEMENT_H_