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

components/tracing/child/child_memory_dump_manager_delegate_impl.h

Index: components/tracing/child/child_memory_dump_manager_delegate_impl.h
diff --git a/components/tracing/child/child_memory_dump_manager_delegate_impl.h b/components/tracing/child/child_memory_dump_manager_delegate_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..fc27d96f279dc284ddcff403d2969832b26e3680
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+++ b/components/tracing/child/child_memory_dump_manager_delegate_impl.h
@@ -0,0 +1,85 @@
+// 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 COMPONENTS_TRACING_CHILD_CHILD_MEMORY_DUMP_MANAGER_DELEGATE_IMPL_H_
+#define COMPONENTS_TRACING_CHILD_CHILD_MEMORY_DUMP_MANAGER_DELEGATE_IMPL_H_
+
+#include "base/trace_event/memory_dump_manager.h"
+
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/singleton.h"
+#include "base/synchronization/lock.h"
+#include "components/tracing/tracing_export.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace tracing {
+
+class ChildTraceMessageFilter;
+
+// This class is a simple proxy class between the MemoryDumpManager and the
+// ChildTraceMessageFilter. It's only purpose is to adapt the lifetime of
+// CTMF to the demands of MDM, which expects the delegate to be thread-safe
+// and long lived. CTMF, instead, can be torn down during browser shutdown.
+// This class is registered as MDM delegate in child processes and handles
+// gracefully (and thread-safely) failures in the case of a lack of the CTMF.
+class TRACING_EXPORT ChildMemoryDumpManagerDelegateImpl
+    : public base::trace_event::MemoryDumpManagerDelegate {
+ public:
+  static ChildMemoryDumpManagerDelegateImpl* GetInstance();
+
+  // base::trace_event::MemoryDumpManagerDelegate implementation.
+  void RequestGlobalMemoryDump(
+      const base::trace_event::MemoryDumpRequestArgs& args,
+      const base::trace_event::MemoryDumpCallback& callback) override;
+  uint64_t GetTracingProcessId() const override;
+
+  void SetChildTraceMessageFilter(ChildTraceMessageFilter* ctmf);
+
+  // Pass kInvalidTracingProcessId to invalidate the id.
+  void set_tracing_process_id(uint64_t id) {
+    DCHECK(tracing_process_id_ ==
+               base::trace_event::MemoryDumpManager::kInvalidTracingProcessId ||
+           id ==
+               base::trace_event::MemoryDumpManager::kInvalidTracingProcessId ||
+           id == tracing_process_id_);
+    tracing_process_id_ = id;
+  }
+
+ protected:
+  // Make CreateProcessDump() visible to ChildTraceMessageFilter.
+  friend class ChildTraceMessageFilter;
+
+ private:
+  friend struct base::DefaultSingletonTraits<
+      ChildMemoryDumpManagerDelegateImpl>;
+
+  ChildMemoryDumpManagerDelegateImpl();
+  ~ChildMemoryDumpManagerDelegateImpl() override;
+
+  ChildTraceMessageFilter* ctmf_;  // Not owned.
+
+  // The SingleThreadTaskRunner where the |ctmf_| lives.
+  // It is NULL iff |cmtf_| is NULL.
+  scoped_refptr<base::SingleThreadTaskRunner> ctmf_task_runner_;
+
+  // Protects from concurrent access to |ctmf_task_runner_| to allow
+  // RequestGlobalMemoryDump to be called from arbitrary threads.
+  base::Lock lock_;
+
+  // The unique id of the child process, created for tracing and is expected to
+  // be valid only when tracing is enabled.
+  uint64_t tracing_process_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChildMemoryDumpManagerDelegateImpl);
+};
+
+}  // namespace tracing
+
+#endif  // COMPONENTS_TRACING_CHILD_CHILD_MEMORY_DUMP_MANAGER_DELEGATE_IMPL_H_