memory-infra: Change discardable memory dump provider to use shared m…

…emory edges

The discardable memory dump provider uses SharedMemory and should be
using the edges created by the new SharedMemoryTracker.

Bug: 661257
Change-Id: Ie20395d7696089c74ab5bdce0e6b09d66e564805
Reviewed-on: https://chromium-review.googlesource.com/607088
Reviewed-by: Hajime Hoshi <hajimehoshi@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: David Reveman <reveman@chromium.org>
Commit-Queue: Siddhartha S <ssid@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493566}

base/memory/discardable_shared_memory.h

@@ -69,6 +69,13 @@ class BASE_EXPORT DiscardableSharedMemory {
   // Returns a shared memory handle for this DiscardableSharedMemory object.
   SharedMemoryHandle handle() const { return shared_memory_.handle(); }
 
+  // Returns an ID for the shared memory region. This is ID of the mapped region
+  // consistent across all processes and is valid as long as the region is not
+  // unmapped.
+  const UnguessableToken& mapped_id() const {
+    return shared_memory_.mapped_id();
+  }
+
   // Locks a range of memory so that it will not be purged by the system.
   // The range of memory must be unlocked. The result of trying to lock an
   // already locked range is undefined. |offset| and |length| must both be

components/discardable_memory/common/discardable_shared_memory_heap.cc

@@ -427,22 +427,16 @@ void DiscardableSharedMemoryHeap::OnMemoryDump(
           ->GetTracingProcessId();
   base::trace_event::MemoryAllocatorDumpGuid shared_segment_guid =
       GetSegmentGUIDForTracing(tracing_process_id, segment_id);
-  // TODO(ssid): Make this weak once the GUID created is consistent
-  // crbug.com/661257.
-  pmd->CreateSharedGlobalAllocatorDump(shared_segment_guid);
-
-  // The size is added to the global dump so that it gets propagated to both the
-  // dumps associated.
-  pmd->GetSharedGlobalAllocatorDump(shared_segment_guid)
-      ->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
-                  base::trace_event::MemoryAllocatorDump::kUnitsBytes,
-                  allocated_objects_size_in_bytes);
 
   // By creating an edge with a higher |importance| (w.r.t. browser-side dumps)
   // the tracing UI will account the effective size of the segment to the
   // client.
   const int kImportance = 2;
-  pmd->AddOwnershipEdge(segment_dump->guid(), shared_segment_guid, kImportance);
+  auto shared_memory_guid = shared_memory->mapped_id();
+  segment_dump->AddString("id", "hash", shared_memory_guid.ToString());
+  pmd->CreateWeakSharedMemoryOwnershipEdge(segment_dump->guid(),
+                                           shared_segment_guid,
+                                           shared_memory_guid, kImportance);
 }
 
 // static

components/discardable_memory/service/discardable_shared_memory_manager.cc

@@ -302,7 +302,8 @@ bool DiscardableSharedMemoryManager::OnMemoryDump(
       if (!segment->memory()->mapped_size())
         continue;
 
-      // The "size" will be inherited form the shared global dump.
+      // TODO(ssid): The "size" should be inherited from the shared memory dump,
+      // crbug.com/661257.
       std::string dump_name = base::StringPrintf(
           "discardable/process_%x/segment_%d", client_id, segment_id);
       base::trace_event::MemoryAllocatorDump* dump =
@@ -327,24 +328,12 @@ bool DiscardableSharedMemoryManager::OnMemoryDump(
       base::trace_event::MemoryAllocatorDumpGuid shared_segment_guid =
           DiscardableSharedMemoryHeap::GetSegmentGUIDForTracing(
               client_tracing_id, segment_id);
-      pmd->CreateSharedGlobalAllocatorDump(shared_segment_guid);
-      pmd->AddOwnershipEdge(dump->guid(), shared_segment_guid);
-
-#if defined(COUNT_RESIDENT_BYTES_SUPPORTED)
-      if (args.level_of_detail ==
-          base::trace_event::MemoryDumpLevelOfDetail::DETAILED) {
-        size_t resident_size =
-            base::trace_event::ProcessMemoryDump::CountResidentBytes(
-                segment->memory()->memory(), segment->memory()->mapped_size());
-
-        // This is added to the global dump since it has to be attributed to
-        // both the allocator dumps involved.
-        pmd->GetSharedGlobalAllocatorDump(shared_segment_guid)
-            ->AddScalar("resident_size",
-                        base::trace_event::MemoryAllocatorDump::kUnitsBytes,
-                        static_cast<uint64_t>(resident_size));
-      }
-#endif  // defined(COUNT_RESIDENT_BYTES_SUPPORTED)
+
+      auto shared_memory_guid = segment->memory()->mapped_id();
+      dump->AddString("id", "hash", shared_memory_guid.ToString());
+      pmd->CreateSharedMemoryOwnershipEdge(dump->guid(), shared_segment_guid,
+                                           shared_memory_guid,
+                                           0 /* importance */);
     }
   }
   return true;