[memory-infra] Add API to ProcessMemoryDump to create ownership edges for base::SharedMemory

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 d632d45a7ce5bb2eb509bbbc42b8080b7c574c27..51587e0b29bec08eb566a743d4d0b2d738c70777 100644
--- a/base/trace_event/process_memory_dump.h
+++ b/base/trace_event/process_memory_dump.h
@@ -30,6 +30,9 @@
 #endif
 
 namespace base {
+
+class UnguessableToken;
+
 namespace trace_event {
 
 class MemoryDumpSessionState;
@@ -148,6 +151,34 @@ class BASE_EXPORT ProcessMemoryDump {
                                    const MemoryAllocatorDumpGuid& target,
                                    int importance);
 
+  // Creates ownership edges for memory backed by base::SharedMemory. Handles
+  // the case of cross process sharing and importnace of ownership for the case
+  // with and without the base::SharedMemory dump provider. The new version
+  // should just use global dumps created by SharedMemoryTracker and this
+  // function handles the transition until we get SharedMemory IDs through mojo
+  // channel crbug.com/713763.
+  // |client_local_dump_guid| The guid of the local dump created by the client
+  // of base::SharedMemory.
+  // |client_global_dump_guid| The global guid given by the clients to create
+  // ownership edges of their own. These global dumps will no longer be required
+  // after the transition.
+  // |shared_memory_guid| The ID of the base::SharedMemory that is assigned
+  // globally, used to create global dump edges in the new model.
+  // |importance| Importance of the global dump edges to say if the current
+  // process owns the memory segment.
+  // |is_weak| Tells if the global dump created should be a weak dump.
+  void CreateSharedMemoryOwnershipEdge(
+      const MemoryAllocatorDumpGuid& client_local_dump_guid,
+      const MemoryAllocatorDumpGuid& client_global_dump_guid,
+      const UnguessableToken& shared_memory_guid,
+      int importance);
+  void CreateWeakSharedMemoryOwnershipEdge(
+      const MemoryAllocatorDumpGuid& client_local_dump_guid,
+      const MemoryAllocatorDumpGuid& client_global_dump_guid,
+      const UnguessableToken& shared_memory_guid,
+      int importance,
+      bool is_weak);

[hajimehoshi, 2017/06/07 04:58:04]

Exposing the last argument |is_weak| is odd. I'd create a private function
CreateWeakSharedMemoryOwnershipEdgeImpl taking this boolean argument, and make
CreateWeakSharedMemoryOwnershipEdge call the Impl with true value.

[ssid, 2017/06/08 00:05:58]

Oh yes. fixed.

+
   const AllocatorDumpEdgesMap& allocator_dumps_edges_for_testing() const {
     return allocator_dumps_edges_;
   }