[memory-infra] Add method to override importance of ownership edges

base/trace_event/process_memory_dump.h

Index: base/trace_event/process_memory_dump.h
diff --git a/base/trace_event/process_memory_dump.h b/base/trace_event/process_memory_dump.h
index 45a973964231fa7d794b2be72d3175871970720b..d632d45a7ce5bb2eb509bbbc42b8080b7c574c27 100644
--- a/base/trace_event/process_memory_dump.h
+++ b/base/trace_event/process_memory_dump.h
@@ -7,6 +7,7 @@
 
 #include <stddef.h>
 
+#include <map>
 #include <unordered_map>
 #include <vector>
 
@@ -43,6 +44,7 @@ class BASE_EXPORT ProcessMemoryDump {
     MemoryAllocatorDumpGuid target;
     int importance;
     const char* type;
+    bool overridable;
   };
 
   // Maps allocator dumps absolute names (allocator_name/heap/subheap) to
@@ -53,6 +55,10 @@ class BASE_EXPORT ProcessMemoryDump {
   using HeapDumpsMap =
       std::unordered_map<std::string, std::unique_ptr<TracedValue>>;
 
+  // Stores allocator dump edges indexed by source allocator dump GUID.
+  using AllocatorDumpEdgesMap =
+      std::map<MemoryAllocatorDumpGuid, MemoryAllocatorDumpEdge>;
+
 #if defined(COUNT_RESIDENT_BYTES_SUPPORTED)
   // Returns the number of bytes in a kernel memory page. Some platforms may
   // have a different value for kernel page sizes from user page sizes. It is
@@ -135,7 +141,14 @@ class BASE_EXPORT ProcessMemoryDump {
   void AddOwnershipEdge(const MemoryAllocatorDumpGuid& source,
                         const MemoryAllocatorDumpGuid& target);
 
-  const std::vector<MemoryAllocatorDumpEdge>& allocator_dumps_edges() const {
+  // Adds edges that can be overriden by a later or earlier call to
+  // AddOwnershipEdge() with the same source and target with a different
+  // |importance| value.
+  void AddOverridableOwnershipEdge(const MemoryAllocatorDumpGuid& source,
+                                   const MemoryAllocatorDumpGuid& target,
+                                   int importance);
+
+  const AllocatorDumpEdgesMap& allocator_dumps_edges_for_testing() const {
     return allocator_dumps_edges_;
   }
 
@@ -200,7 +213,7 @@ class BASE_EXPORT ProcessMemoryDump {
   scoped_refptr<MemoryDumpSessionState> session_state_;
 
   // Keeps track of relationships between MemoryAllocatorDump(s).
-  std::vector<MemoryAllocatorDumpEdge> allocator_dumps_edges_;
+  AllocatorDumpEdgesMap allocator_dumps_edges_;
 
   // Level of detail of the current dump.
   const MemoryDumpArgs dump_args_;