[tracing] Add sqlite memory statistics to tracing.

sql/connection.h

 // Copyright (c) 2012 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 SQL_CONNECTION_H_
 #define SQL_CONNECTION_H_
 
 #include <stdint.h>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time/time.h"
+#include "base/trace_event/memory_dump_provider.h"
 #include "sql/sql_export.h"
 
 struct sqlite3;
 struct sqlite3_stmt;
 
 namespace base {
 class FilePath;
 class HistogramBase;
 }
 
@@ skipping 64 matching lines @@
   TimeSource() {}
   virtual ~TimeSource() {}
 
   // Return the current time (by default base::TimeTicks::Now()).
   virtual base::TimeTicks Now();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TimeSource);
 };
 
-class SQL_EXPORT Connection {
+class SQL_EXPORT Connection : public base::trace_event::MemoryDumpProvider {
  private:

[Primiano Tucci (use gerrit), 2015/09/30 10:26:56]

Just to have a rough idea, how many connections can we have open?
Is it a few, dozens or hundreds?

[ssid, 2015/10/02 17:06:10]

It is usually less than 2 dozens.

   class StatementRef;  // Forward declaration, see real one below.
 
  public:
   // The database is opened by calling Open[InMemory](). Any uncommitted
   // transactions will be rolled back when this object is deleted.
   Connection();
-  ~Connection();
+  ~Connection() override;
 
   // Pre-init configuration ----------------------------------------------------
 
   // Sets the page size that will be used when creating a new database. This
   // must be called before Init(), and will only have an effect on new
   // databases.
   //
   // From sqlite.org: "The page size must be a power of two greater than or
   // equal to 512 and less than or equal to SQLITE_MAX_PAGE_SIZE. The maximum
   // value for SQLITE_MAX_PAGE_SIZE is 32768."
@@ skipping 330 matching lines @@
   // running the following statement at a sqlite3 command-line:
   //   SELECT type, name, tbl_name, sql FROM sqlite_master ORDER BY 1, 2, 3, 4;
   std::string GetSchema() const;
 
   // Clients which provide an error_callback don't see the
   // error-handling at the end of OnSqliteError().  Expose to allow
   // those clients to work appropriately with ScopedErrorIgnorer in
   // tests.
   static bool ShouldIgnoreSqliteError(int error);
 
+  // base::trace_event::MemoryDumpProvider implementation.
+  bool OnMemoryDump(
+      const base::trace_event::MemoryDumpArgs& args,
+      base::trace_event::ProcessMemoryDump* process_memory_dump) override;
+
  private:
   // For recovery module.
   friend class Recovery;
 
   // Allow test-support code to set/reset error ignorer.
   friend class ScopedErrorIgnorer;
 
   // Statement accesses StatementRef which we don't want to expose to everybody
   // (they should go through Statement).
   friend class Statement;
@@ skipping 229 matching lines @@
   // Source for timing information, provided to allow tests to inject time
   // changes.
   scoped_ptr<TimeSource> clock_;
 
   DISALLOW_COPY_AND_ASSIGN(Connection);
 };
 
 }  // namespace sql
 
 #endif  // SQL_CONNECTION_H_