Use leveldb_env::OpenDB() to open leveldb databases.

third_party/leveldatabase/env_chromium.cc

Index: third_party/leveldatabase/env_chromium.cc
diff --git a/third_party/leveldatabase/env_chromium.cc b/third_party/leveldatabase/env_chromium.cc
index 7a0f4ad03f18b378b52d94398510e54e6ccb05a4..c3f730dd45928f0cdc1be2d56352439398f4c342 100644
--- a/third_party/leveldatabase/env_chromium.cc
+++ b/third_party/leveldatabase/env_chromium.cc
@@ -1193,11 +1193,16 @@ class DBTracker::MemoryDumpProvider
  public:
   bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                     base::trace_event::ProcessMemoryDump* pmd) override {
+    // Don't dump in background mode ("from the field") until whitelisted.
+    if (args.level_of_detail ==
+        base::trace_event::MemoryDumpLevelOfDetail::BACKGROUND) {
+      return true;
+    }
+
     auto db_visitor = [](const base::trace_event::MemoryDumpArgs& args,
                          base::trace_event::ProcessMemoryDump* pmd,
                          TrackedDB* db) {
-      std::string db_dump_name = base::StringPrintf(
-          "leveldatabase/0x%" PRIXPTR, reinterpret_cast<uintptr_t>(db));
+      std::string db_dump_name = DBTracker::GetMemoryDumpName(db);
       auto* db_dump = pmd->CreateAllocatorDump(db_dump_name.c_str());
 
       uint64_t db_memory_usage = 0;
@@ -1245,11 +1250,17 @@ DBTracker* DBTracker::GetInstance() {
   return instance;
 }
 
+std::string DBTracker::GetMemoryDumpName(leveldb::DB* tracked_db) {
+  return base::StringPrintf("leveldatabase/0x%" PRIXPTR,

[pwnall, 2017/07/07 22:30:29]

nit: I'd prefer that GetMemoryDumpName() DCHECKs that tracked_db is in the
linked list. I can do it if you don't get around to.

[DmitrySkiba, 2017/07/17 22:09:25]

I can see value in that DCHECK, but I'm not sure what is the right way to add
it. The thing is that GetMemoryDumpName() is called from VisitDatabases visitor
right now, so we either have to split it in two (internal version that doesn't
lock, external that locks), or we introduce two GetMemoryDumpName() versions:
one that takes DB and has DHCECK (and calls another), and the one that takes
TrackedDB, and doesn't lock. Neither option is ideal to me. I suggest we move
further with this implementation, and and continue searching for a proper way in
a follow-up CL (which I'll create).

+                            reinterpret_cast<uintptr_t>(tracked_db));
+}
+
 leveldb::Status DBTracker::OpenDatabase(const leveldb::Options& options,
                                         const std::string& name,
                                         TrackedDB** dbptr) {
   leveldb::DB* db = nullptr;
   auto status = leveldb::DB::Open(options, name, &db);
+  CHECK((status.ok() && db) || (!status.ok() && !db));
   if (status.ok()) {
     // TrackedDBImpl ctor adds the instance to the tracker.
     *dbptr = new TrackedDBImpl(GetInstance(), name, db);