Add renderer-side client for LeakDetectorRemoteController

chrome/renderer/leak_detector_remote_client.cc

+// Copyright 2016 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 "chrome/renderer/leak_detector_remote_client.h"
+
+#include "base/bind.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "components/metrics/proto/memory_leak_report.pb.h"
+#include "content/public/common/service_registry.h"
+#include "content/public/renderer/render_thread.h"
+#include "mojo/public/cpp/bindings/interface_request.h"
+
+LeakDetectorRemoteClient::LeakDetectorRemoteClient() {
+  // Connect to Mojo service.
+  content::RenderThread::Get()->GetServiceRegistry()->ConnectToRemoteService(
+      mojo::GetProxy(&remote_service_));
+
+  remote_service_->GetParams(
+      base::Bind(&LeakDetectorRemoteClient::OnParamsReceived,
+                 base::Unretained(this)));
+}
+
+LeakDetectorRemoteClient::~LeakDetectorRemoteClient() {
+  metrics::LeakDetector::GetInstance()->RemoveObserver(this);

[Ilya Sherman, 2016/06/16 18:14:20]

Is it safe to call RemoveObserver() if AddObserver() was never called, i.e. if
OnParamsReceived() was never triggered?  (The most common pattern to solve this
problem is to assign a member variable within OnParamsReceived(), which
unregisters as an observer upon destruction.  That is, the Resource Acquisition
Is Initialization pattern.)

[Simon Que, 2016/06/17 01:30:38]

Yes, the observers are added to base::ObserverList, whose RemoveObserver() func
safely handles the case of an observer not being present in the list.

[Ilya Sherman, 2016/06/17 01:32:50]

Okay.  In that case, LGTM with the added documentation for use of
base::Unretained() above.

+}
+
+void LeakDetectorRemoteClient::OnParamsReceived(mojo::String result) {
+  if (result.empty())
+    return;
+
+  metrics::MemoryLeakReportProto::Params params;
+  bool params_decoded = params.ParseFromString(result.get());
+  DCHECK(params_decoded);
+
+  metrics::LeakDetector* detector = metrics::LeakDetector::GetInstance();
+  detector->AddObserver(this);
+  detector->Init(params, base::ThreadTaskRunnerHandle::Get());
+}
+
+void LeakDetectorRemoteClient::OnLeaksFound(
+    const std::vector<metrics::MemoryLeakReportProto>& reports) {
+  // TODO(sque): Handle reports.
+}