[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..da30ba262c4a7b534f4bfd2b51c190323ee3d145 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";
+
 }  // namespace
 
 DiscardableSharedMemoryHeap::Span::Span(
@@ -225,6 +227,7 @@ size_t DiscardableSharedMemoryHeap::GetSizeOfFreeLists() const {
 
 bool DiscardableSharedMemoryHeap::OnMemoryDump(
     base::trace_event::ProcessMemoryDump* pmd) {
+  CreateAllocatedObjectsDump(pmd);
   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,
@@ -390,6 +393,21 @@ void DiscardableSharedMemoryHeap::OnMemoryDump(
   pmd->AddOwnershipEdge(segment_dump->guid(), shared_segment_guid, kImportance);
 }
 
+void DiscardableSharedMemoryHeap::CreateAllocatedObjectsDump(

[petrcermak, 2015/07/29 16:38:59]

nit: I think you should say "// static" above the function definition.

[ssid, 2015/07/29 16:57:37]

Done.

+    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 contain kDiscardableSegmentsDumpName

[petrcermak, 2015/07/29 16:38:59]

This is reversed. The dump called kDiscardableSegmentsDumpName will contain
discardable memory segments.

[ssid, 2015/07/29 16:57:37]

Done.

+  // as the root and will own any sub-allocations with kAllocatedObjectsDumpName

[petrcermak, 2015/07/29 16:38:59]

Probably "parent" or "ancestor" instead of "root" ("discardable/" is the root)
(twice).

[petrcermak, 2015/07/29 16:38:59]

s/own/be owned by/

[ssid, 2015/07/29 16:57:37]

Done.

+  // as the root.
+  pmd->AddOwnershipEdge(objects_dump->guid(),
+                        discardable_segments_dump->guid());
+}
+
 // static
 base::trace_event::MemoryAllocatorDumpGuid
 DiscardableSharedMemoryHeap::GetSegmentGUIDForTracing(uint64 tracing_process_id,