[tracing] Send smaps file desciptor to child process for tracing

components/tracing/child_memory_dump_manager_delegate_impl.h

 // 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_MEMORY_DUMP_MANAGER_DELEGATE_IMPL_H_
 #define COMPONENTS_TRACING_CHILD_MEMORY_DUMP_MANAGER_DELEGATE_IMPL_H_
 
 #include "base/trace_event/memory_dump_manager.h"
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/singleton.h"
 #include "base/synchronization/lock.h"
+#include "components/tracing/tracing_messages.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 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 GetTracingProcessId() const override;
 
   void SetChildTraceMessageFilter(ChildTraceMessageFilter* ctmf);
 
-  // Pass kInvalidTracingProcessId to invalidate the id.
-  void set_tracing_process_id(uint64 id) {
-    DCHECK_IMPLIES(
-        tracing_process_id_ !=
-            base::trace_event::MemoryDumpManager::kInvalidTracingProcessId,
-        id == base::trace_event::MemoryDumpManager::kInvalidTracingProcessId ||
-            id == tracing_process_id_);
-    tracing_process_id_ = id;
-  }
+  // Set the child process tracing id and file descriptors for tracing. This
+  // sets tracing_process_id and sends the file decriptor to relevant dump
+  // providers. ResetMemoryTracingInfo should be called at the end of tracing to
+  // close these files which are not supposed to be used in child if not for
+  // tracing.
+  void SetMemoryTracingInfo(
+      const TracingMsg_MemoryTracingInfo& memory_tracing_info);
+
+  // Resets the tracing process id and resets the relevant dump providers.
+  void ResetMemoryTracingInfo();
 
  protected:
   // Make CreateProcessDump() visible to ChildTraceMessageFilter.
   friend class ChildTraceMessageFilter;
 
  private:
   friend struct base::DefaultSingletonTraits<
       ChildMemoryDumpManagerDelegateImpl>;
 
   ChildMemoryDumpManagerDelegateImpl();
@@ skipping 12 matching lines @@
   // The unique id of the child process, created for tracing and is expected to
   // be valid only when tracing is enabled.
   uint64 tracing_process_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildMemoryDumpManagerDelegateImpl);
 };
 
 }  // namespace tracing
 
 #endif  // COMPONENTS_TRACING_CHILD_MEMORY_DUMP_MANAGER_DELEGATE_IMPL_H_