Generate globally (cross-process) unique IDs for memory tracing dumps

base/trace_event/memory_dump_manager.cc

Index: base/trace_event/memory_dump_manager.cc
diff --git a/base/trace_event/memory_dump_manager.cc b/base/trace_event/memory_dump_manager.cc
index ec7651fe4447b72e4af9ab7bce31cbc5052b11b2..2c4b18e1dd74c9232262c7e94e1ccf8808b5be89 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -115,9 +115,8 @@ void MemoryDumpManager::RequestGlobalDump(
   if (!UNLIKELY(subtle::NoBarrier_Load(&memory_tracing_enabled_)))
     return;
 
-  // TODO(primiano): Make guid actually unique (cross-process) by hashing it
-  // with the PID. See crbug.com/462931 for details.
-  const uint64 guid = g_next_guid.GetNext();
+  const uint64 guid =
+      TraceLog::GetInstance()->MangleEventId(g_next_guid.GetNext());
 
   // The delegate_ is supposed to be thread safe, immutable and long lived.
   // No need to keep the lock after we ensure that a delegate has been set.