[tracing] Add separate dump provider for sql connection

The sql connection memory dump is not thread safe since the connections
can get deleted while a dump is happening. To make this thread safe,
this CL introduces a dump provider class owned by the connection. This
class holds a lock when dumping and deleting the database. Also, to
workaround thread safe dump provider registration, it uses the
UnregisterAndDeleteDumpProviderAsync api added in crrev.com/1430073002.

BUG=466141

Review URL: https://codereview.chromium.org/1434993002

Cr-Commit-Position: refs/heads/master@{#369161}

1 files changed, 41 insertions, 0 deletions

diff --git a/sql/connection_memory_dump_provider.h b/sql/connection_memory_dump_provider.h
new file mode 100644
index 0000000..bcad0f8
--- /dev/null
+++ b/sql/connection_memory_dump_provider.h
@@ -0,0 +1,41 @@
+// Copyright 2015 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_MEMORY_DUMP_PROVIDER_H
+#define SQL_CONNECTION_MEMORY_DUMP_PROVIDER_H
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/synchronization/lock.h"
+#include "base/trace_event/memory_dump_provider.h"
+
+struct sqlite3;
+
+namespace sql {
+
+class ConnectionMemoryDumpProvider
+    : public base::trace_event::MemoryDumpProvider {
+ public:
+  ConnectionMemoryDumpProvider(sqlite3* db, const std::string& name);
+  ~ConnectionMemoryDumpProvider() override;
+
+  void ResetDatabase();
+
+  // base::trace_event::MemoryDumpProvider implementation.
+  bool OnMemoryDump(
+      const base::trace_event::MemoryDumpArgs& args,
+      base::trace_event::ProcessMemoryDump* process_memory_dump) override;
+
+ private:
+  sqlite3* db_;  // not owned.
+  base::Lock lock_;
+  std::string connection_name_;
+
+  DISALLOW_COPY_AND_ASSIGN(ConnectionMemoryDumpProvider);
+};
+
+}  // namespace sql
+
+#endif  // SQL_CONNECTION_MEMORY_DUMP_PROVIDER_H