Revert of memory-infra: Finish moving to Mojo (2nd attempt)

components/tracing/child/child_memory_dump_manager_delegate_impl.cc

Index: components/tracing/child/child_memory_dump_manager_delegate_impl.cc
diff --git a/components/tracing/child/child_memory_dump_manager_delegate_impl.cc b/components/tracing/child/child_memory_dump_manager_delegate_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f0c4517b2ea4b44dedf3d0f9519402155f08ec67
--- /dev/null
+++ b/components/tracing/child/child_memory_dump_manager_delegate_impl.cc
@@ -0,0 +1,114 @@
+// 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 "components/tracing/child/child_memory_dump_manager_delegate_impl.h"
+
+#include "base/single_thread_task_runner.h"
+#include "build/build_config.h"
+#include "components/tracing/child/child_trace_message_filter.h"
+#include "components/tracing/common/process_metrics_memory_dump_provider.h"
+
+namespace tracing {
+
+namespace {
+void AbortDumpRequest(const base::trace_event::MemoryDumpRequestArgs& args,
+                      const base::trace_event::MemoryDumpCallback& callback) {
+  if (!callback.is_null())
+    callback.Run(args.dump_guid, false /* success */);
+}
+}  // namespace
+
+// static
+ChildMemoryDumpManagerDelegateImpl*
+ChildMemoryDumpManagerDelegateImpl::GetInstance() {
+  return base::Singleton<
+      ChildMemoryDumpManagerDelegateImpl,
+      base::LeakySingletonTraits<ChildMemoryDumpManagerDelegateImpl>>::get();
+}
+
+ChildMemoryDumpManagerDelegateImpl::ChildMemoryDumpManagerDelegateImpl()
+    : ctmf_(nullptr),
+      tracing_process_id_(
+          base::trace_event::MemoryDumpManager::kInvalidTracingProcessId) {
+}
+
+ChildMemoryDumpManagerDelegateImpl::~ChildMemoryDumpManagerDelegateImpl() {}
+
+void ChildMemoryDumpManagerDelegateImpl::SetChildTraceMessageFilter(
+    ChildTraceMessageFilter* ctmf) {
+  auto* task_runner = ctmf ? (ctmf->ipc_task_runner()) : nullptr;
+  // Check that we are either registering the CTMF or tearing it down, but not
+  // replacing a valid instance with another one (should never happen).
+  DCHECK(!ctmf_ || (!ctmf && ctmf_task_runner_));
+  ctmf_ = ctmf;
+
+  {
+    base::AutoLock lock(lock_);
+    ctmf_task_runner_ = task_runner;
+  }
+
+  if (ctmf) {
+    base::trace_event::MemoryDumpManager::GetInstance()->Initialize(
+      this /* delegate */, false /* is_coordinator */);
+
+#if !defined(OS_LINUX) && !defined(OS_NACL)
+    // On linux the browser process takes care of dumping process metrics.
+    // The child process is not allowed to do so due to BPF sandbox.
+    tracing::ProcessMetricsMemoryDumpProvider::RegisterForProcess(
+        base::kNullProcessId);
+#endif
+  }
+}
+
+// Invoked in child processes by the MemoryDumpManager.
+void ChildMemoryDumpManagerDelegateImpl::RequestGlobalMemoryDump(
+    const base::trace_event::MemoryDumpRequestArgs& args,
+    const base::trace_event::MemoryDumpCallback& callback) {
+  // RequestGlobalMemoryDump can be called on any thread, cannot access
+  // ctmf_task_runner_ as it could be racy.
+  scoped_refptr<base::SingleThreadTaskRunner> ctmf_task_runner;
+  {
+    base::AutoLock lock(lock_);
+    ctmf_task_runner = ctmf_task_runner_;
+  }
+
+  // Bail out if we receive a dump request from the manager before the
+  // ChildTraceMessageFilter has been initialized.
+  if (!ctmf_task_runner) {
+    VLOG(1) << base::trace_event::MemoryDumpManager::kLogPrefix
+            << " failed because child trace message filter hasn't been"
+            << " initialized";
+    return AbortDumpRequest(args, callback);
+  }
+
+  // Make sure we access |ctmf_| only on the thread where it lives to avoid
+  // races on shutdown.
+  if (!ctmf_task_runner->BelongsToCurrentThread()) {
+    const bool did_post_task = ctmf_task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(&ChildMemoryDumpManagerDelegateImpl::RequestGlobalMemoryDump,
+                   base::Unretained(this), args, callback));
+    if (!did_post_task)
+      return AbortDumpRequest(args, callback);
+    return;
+  }
+
+  // The ChildTraceMessageFilter could have been destroyed while hopping on the
+  // right thread. If this is the case, bail out.
+  if (!ctmf_) {
+    VLOG(1) << base::trace_event::MemoryDumpManager::kLogPrefix
+            << " failed because child trace message filter was"
+            << " destroyed while switching threads";
+    return AbortDumpRequest(args, callback);
+  }
+
+  // Send the request up to the browser process' MessageDumpmanager.
+  ctmf_->SendGlobalMemoryDumpRequest(args, callback);
+}
+
+uint64_t ChildMemoryDumpManagerDelegateImpl::GetTracingProcessId() const {
+  return tracing_process_id_;
+}
+
+}  // namespace tracing