[tracing] Add SkResourceCache as suballocation to avoid double counting.

content/common/discardable_shared_memory_heap.cc

Index: content/common/discardable_shared_memory_heap.cc
diff --git a/content/common/discardable_shared_memory_heap.cc b/content/common/discardable_shared_memory_heap.cc
index 958fa82554efecf5d9c4dee25bb6206cf7e891c9..b94e5f8d58601d4a05bec05bb9db17b552b8943e 100644
--- a/content/common/discardable_shared_memory_heap.cc
+++ b/content/common/discardable_shared_memory_heap.cc
@@ -22,6 +22,8 @@ bool IsInFreeList(DiscardableSharedMemoryHeap::Span* span) {
   return span->previous() || span->next();
 }
 
+const char kDiscardableSegmentsDumpName[] = "discardable/segments";

[reveman, 2015/07/30 16:00:59]

We've been avoiding explicit constants for dump name strings. Is this different
or should we just use 'base::StringPrintf("discardable/segments/segment_%d",
...' below instead?

Btw, it would be a bit more appropriate if the DiscardableMemoryAllocator
controlled this prefix and just passed it to
DiscardableSharedMemoryHeap::OnMemoryDump but no need to fix that in this CL.

[ssid, 2015/07/30 20:05:15]

Done.

+
 }  // namespace
 
 DiscardableSharedMemoryHeap::Span::Span(
@@ -225,6 +227,7 @@ size_t DiscardableSharedMemoryHeap::GetSizeOfFreeLists() const {
 
 bool DiscardableSharedMemoryHeap::OnMemoryDump(
     base::trace_event::ProcessMemoryDump* pmd) {
+  CreateAllocatedObjectsDump(pmd);

[reveman, 2015/07/30 16:00:59]

I think it should be the responsibility of the DiscardableMemoryAllocator to
create this node.

[ssid, 2015/07/30 20:05:15]

Yes, But then since i placed the method in this class, i called it here. Moved
the method and the calls to allocator.

   std::for_each(
       memory_segments_.begin(), memory_segments_.end(),
       [pmd](const ScopedMemorySegment* segment) {
@@ -356,8 +359,8 @@ void DiscardableSharedMemoryHeap::OnMemoryDump(
     offset += span->length_;
   }
 
-  std::string segment_dump_name =
-      base::StringPrintf("discardable/segment_%d", segment_id);
+  std::string segment_dump_name = base::StringPrintf(
+      "%s/segment_%d", kDiscardableSegmentsDumpName, segment_id);
   base::trace_event::MemoryAllocatorDump* segment_dump =
       pmd->CreateAllocatorDump(segment_dump_name);
   segment_dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
@@ -391,6 +394,22 @@ void DiscardableSharedMemoryHeap::OnMemoryDump(
 }
 
 // static
+void DiscardableSharedMemoryHeap::CreateAllocatedObjectsDump(
+    base::trace_event::ProcessMemoryDump* pmd) {
+  base::trace_event::MemoryAllocatorDump* objects_dump =
+      pmd->CreateAllocatorDump(
+          base::DiscardableSharedMemory::kAllocatedObjectsDumpName);
+  base::trace_event::MemoryAllocatorDump* discardable_segments_dump =
+      pmd->CreateAllocatorDump(kDiscardableSegmentsDumpName);
+
+  // The discardable memory segments will be dumped with
+  // kDiscardableSegmentsDumpName as the parent and will be owned by
+  // sub-allocations dumped with kAllocatedObjectsDumpName as their parent.
+  pmd->AddOwnershipEdge(objects_dump->guid(),
+                        discardable_segments_dump->guid());
+}
+
+// static
 base::trace_event::MemoryAllocatorDumpGuid
 DiscardableSharedMemoryHeap::GetSegmentGUIDForTracing(uint64 tracing_process_id,
                                                       int32 segment_id) {