memory-infra: Add peak-detector skeleton.

base/trace_event/memory_dump_provider_info.h

 // Copyright 2017 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 BASE_TRACE_EVENT_MEMORY_DUMP_PROVIDER_INFO_H_
 #define BASE_TRACE_EVENT_MEMORY_DUMP_PROVIDER_INFO_H_
 
 #include <memory>
 #include <set>
 
+#include "base/base_export.h"
 #include "base/memory/ref_counted.h"
 #include "base/trace_event/memory_dump_provider.h"
 
 namespace base {
 
 class SequencedTaskRunner;
 
 namespace trace_event {
 
 // Wraps a MemoryDumpProvider (MDP), which is registered via
@@ skipping 13 matching lines @@
 //   MDM's |dump_providers_| list.
 // - In most cases, the only refptr (in the |dump_providers_| list) is destroyed
 //   by MDM::UnregisterDumpProvider().
 // - However, when MDM starts a dump, the list of refptrs is copied into the
 //   ProcessMemoryDumpAsyncState. That list is pruned as MDP(s) are invoked.
 // - If UnregisterDumpProvider() is called on a non-thread-bound MDP while a
 //   dump is in progress, the extar extra of the handle is destroyed in
 //   MDM::SetupNextMemoryDump() or MDM::InvokeOnMemoryDump(), when the copy
 //   inside ProcessMemoryDumpAsyncState is erase()-d.
 // - The PeakDetector can keep extra refptrs when enabled.
-struct MemoryDumpProviderInfo
+struct BASE_EXPORT MemoryDumpProviderInfo
     : public RefCountedThreadSafe<MemoryDumpProviderInfo> {
  public:
   // Define a total order based on the |task_runner| affinity, so that MDPs
   // belonging to the same SequencedTaskRunner are adjacent in the set.
   struct Comparator {
     bool operator()(const scoped_refptr<MemoryDumpProviderInfo>& a,
                     const scoped_refptr<MemoryDumpProviderInfo>& b) const;
   };
   using OrderedSet =
       std::set<scoped_refptr<MemoryDumpProviderInfo>, Comparator>;
@@ skipping 43 matching lines @@
   friend class base::RefCountedThreadSafe<MemoryDumpProviderInfo>;
   ~MemoryDumpProviderInfo();
 
   DISALLOW_COPY_AND_ASSIGN(MemoryDumpProviderInfo);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_MEMORY_DUMP_PROVIDER_INFO_H_