[tracing] Add separate dump provider for sql connection

sql/connection_memory_dump_provider.cc

+// 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.
+
+#include "sql/connection_memory_dump_provider.h"
+
+#include "base/strings/stringprintf.h"
+#include "base/trace_event/process_memory_dump.h"
+#include "third_party/sqlite/sqlite3.h"
+
+namespace sql {
+
+ConnectionMemoryDumpProvider::ConnectionMemoryDumpProvider(
+    sqlite3* db,
+    const std::string& name)
+    : db_(db), name_(name) {
+  DCHECK(db_);

[Primiano Tucci (use gerrit), 2016/01/11 19:27:42]

this dcheck doesn't seem to be really needed as you have a full if below

[ssid, 2016/01/12 12:23:07]

Done.

+}
+
+ConnectionMemoryDumpProvider::~ConnectionMemoryDumpProvider() {}
+
+bool ConnectionMemoryDumpProvider::OnMemoryDump(
+    const base::trace_event::MemoryDumpArgs& args,
+    base::trace_event::ProcessMemoryDump* pmd) {
+  if (args.level_of_detail == base::trace_event::MemoryDumpLevelOfDetail::LIGHT)
+    return true;
+
+  base::AutoLock l(lock_);

[Primiano Tucci (use gerrit), 2016/01/11 19:27:42]

add a comment explaining why you need this lock here.

[ssid, 2016/01/12 12:23:07]

Done.

+  if (!db_) {
+    return false;
+  }
+
+  // The high water mark is not tracked for the following usages.
+  int cache_size, dummy_int;
+  int status;
+  status = sqlite3_db_status(db_, SQLITE_DBSTATUS_CACHE_USED, &cache_size,
+                             &dummy_int, 0 /* resetFlag */);
+  DCHECK_EQ(SQLITE_OK, status);
+  int schema_size;
+  status = sqlite3_db_status(db_, SQLITE_DBSTATUS_SCHEMA_USED, &schema_size,
+                             &dummy_int, 0 /* resetFlag */);
+  DCHECK_EQ(SQLITE_OK, status);
+  int statement_size;
+  status = sqlite3_db_status(db_, SQLITE_DBSTATUS_STMT_USED, &statement_size,
+                             &dummy_int, 0 /* resetFlag */);
+  DCHECK_EQ(SQLITE_OK, status);
+
+  std::string name =
+      base::StringPrintf("sqlite/%s_connection/%p",
+                         name_.empty() ? "Unknown" : name_.c_str(), this);
+  base::trace_event::MemoryAllocatorDump* dump = pmd->CreateAllocatorDump(name);
+  dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
+                  base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                  cache_size + schema_size + statement_size);
+  dump->AddScalar("cache_size",
+                  base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                  cache_size);
+  dump->AddScalar("schema_size",
+                  base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                  schema_size);
+  dump->AddScalar("statement_size",
+                  base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                  statement_size);
+  return true;
+}
+
+}  // namespace sql