[tracing] Prepare for internal async handling of ProcessMemoryDump(s)

So far the internal interface between MemoryDumpManager and its
delegates (TracingControllerImpl on the browser side and
ChildTraceMessageFilter on the child side) has been synchronous,
in the sense that all the MDP.DumpInto() calls were performed
in the current call stack.
The MemoryDumpProviders contract, however, is going to change in the
upcoming CLs to support posting the DumpInto() on other threads.
This requires to change the internal CreateProcessDump() method to
be asynchronous and requires the corresponding bookkeeping.

BUG=478008

Review URL: https://codereview.chromium.org/1089493003

Cr-Commit-Position: refs/heads/master@{#325779}

1 files changed, 2 insertions, 0 deletions

diff --git a/components/tracing/child_trace_message_filter.h b/components/tracing/child_trace_message_filter.h
index 080ea04..a6453a3 100644
--- a/components/tracing/child_trace_message_filter.h
+++ b/components/tracing/child_trace_message_filter.h
@@ -64,6 +64,8 @@ class ChildTraceMessageFilter : public IPC::MessageFilter {
       const scoped_refptr<base::RefCountedString>& events_str_ptr,
       bool has_more_events);
 
+  void OnProcessMemoryDumpDone(uint64 dump_guid, bool success);
+
   IPC::Sender* sender_;
   base::MessageLoopProxy* ipc_message_loop_;