[memory-infra] Make thread check at unregistration stricter for new dump providers

base/trace_event/memory_dump_manager.cc

Index: base/trace_event/memory_dump_manager.cc
diff --git a/base/trace_event/memory_dump_manager.cc b/base/trace_event/memory_dump_manager.cc
index dd67c3155d99c73b07a26bc348eaabdbd7d3afd4..503c836676d756395984fcaa66b4ddefd447fec2 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -47,6 +47,54 @@ const unsigned char kTraceEventArgTypes[] = {TRACE_VALUE_TYPE_CONVERTABLE};
 StaticAtomicSequenceNumber g_next_guid;
 MemoryDumpManager* g_instance_for_testing = nullptr;
 
+// The list of dump providers that are blacklisted from strict checks when
+// unregistration. These providers could potentially cause crashes on build bots

[Primiano Tucci (use gerrit), 2017/01/06 14:00:39]

either "checks on unregistration" or "checks when unregistering".

[ssid, 2017/01/10 23:59:38]

Done.

+// if they do not unregister on right thread.
+// TODO(ssid): Fix all the dump providers to unregister if needed and clear the
+// blacklist, crbug.com/643438.
+const char* kStrictThreadCheckBlacklist[] = {

[Primiano Tucci (use gerrit), 2017/01/06 14:00:39]

+const (consts are never enough), i.e.
const char* const kStrictThreadCheckBlacklist, so would make the array actually
immutable (As the kNamingNotation suggests). Otherwise you end up with a mutable
array to immutable char pointers.

[ssid, 2017/01/10 23:59:38]

Sorry forgot const here.

+    "android::ResourceManagerImpl",
+    "AndroidGraphics",
+    "BrowserGpuMemoryBufferManager",
+    "ClientDiscardableSharedMemoryManager",
+    "ContextProviderCommandBuffer",
+    "DOMStorage",
+    "DiscardableSharedMemoryManager",
+    "FontCaches",
+    "GpuMemoryBufferVideoFramePool",
+    "IndexedDBBackingStore",
+    "LeveldbValueStore",
+    "MemoryCache",
+    "Skia",
+    "Sql",
+    "ThreadLocalEventBuffer",
+    "TraceLog",
+    "URLRequestContext",
+    "V8Isolate",
+    "VpxVideoDecoder",
+    "cc::ResourcePool",
+    "cc::ResourceProvider",
+    "cc::SoftwareImageDecodeCache",
+    "cc::StagingBufferPool",
+    "gpu::BufferManager",
+    "gpu::MappedMemoryManager",
+    "gpu::RenderbufferManager",
+    "gpu::TextureManager",
+    "gpu::TransferBufferManager",
+    "sql::Connection",
+    "SyncDirectory",
+    "BlacklistTestDumpProvider"  // for testing
+};
+
+// Returns true if the name is present in the blacklist.
+bool IsDumpproviderBlackListedForStrictThreadCheck(const char* name) {

[Primiano Tucci (use gerrit), 2017/01/06 14:00:39]

my suggestion is that you keep the array above and:

1)  add a std::unordered_set<base::StringPiece, base::StringPieceHash> to the
MDM instance.

2) In the MDM ctor you do:
thread_check_blacklist_.insert(std::begin(kArray), std::end(kArray)) (or
something like that, not sure if this is possible in one op with stringpiece)

3) and then below during unregistration, where you call this function you just
do
thread_check_blacklist_.count((*mdp_iter)->name)

[ssid, 2017/01/10 23:59:38]

Done.

+  for (auto* str : kStrictThreadCheckBlacklist) {
+    if (strcmp(name, str) == 0)
+      return true;
+  }
+  return false;
+}
+
 // Callback wrapper to hook upon the completion of RequestGlobalDump() and
 // inject trace markers.
 void OnGlobalDumpDone(MemoryDumpCallback wrapped_callback,
@@ -339,7 +387,16 @@ void MemoryDumpManager::UnregisterDumpProviderInternal(
     // - When the provider is removed from |dump_providers_for_polling_|.
     DCHECK(!(*mdp_iter)->owned_dump_provider);
     (*mdp_iter)->owned_dump_provider = std::move(owned_mdp);
-  } else if (subtle::NoBarrier_Load(&memory_tracing_enabled_)) {
+  } else if (!IsDumpproviderBlackListedForStrictThreadCheck(
+                 (*mdp_iter)->name) ||
+             subtle::NoBarrier_Load(&memory_tracing_enabled_)) {
+    // If IsDumpproviderBlackListedForStrictThreadCheck() is true, then the
+    // DCHECK is fired only when tracing is enabled. Otherwise the DCHECK is
+    // fired even when tracing is not enabled (stricter).
+    // TODO(ssid): Remove this condition after removing all the dump providers
+    // in the blacklist and the buildbots are no longer flakily hitting the
+    // DCHECK, crbug.com/643438.
+
     // If you hit this DCHECK, your dump provider has a bug.
     // Unregistration of a MemoryDumpProvider is safe only if:
     // - The MDP has specified a sequenced task runner affinity AND the