Code cleanup and typos in trace_event [NFC]

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>
 
@@ skipping 13 matching lines @@
 // whether it has been disabled, etc.)
 // More importantly, having a refptr to this object guarantees that a MDP that
 // is not thread-bound (hence which can only be unregistered via
 // MDM::UnregisterAndDeleteDumpProviderSoon()) will stay alive as long as the
 // refptr is held.
 //
 // Lifetime:
 // At any time, there is at most one instance of this class for each instance
 // of a given MemoryDumpProvider, but there might be several scoped_refptr
 // holding onto each of this. Specifically:
-// - In nominal conditions, there is a refptr for each registerd MDP in the
+// - In nominal conditions, there is a refptr for each registered MDP in the
 //   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.
@@ skipping 58 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_