memory-infra: Move dump level check to observer and rename session state

base/trace_event/memory_tracing_observer.cc

Index: base/trace_event/memory_tracing_observer.cc
diff --git a/base/trace_event/memory_tracing_observer.cc b/base/trace_event/memory_tracing_observer.cc
index a5b60e48fd7e0dc0565165346024ac102644556c..78c282b6828d0556d6a644fe458d8a3672a55427 100644
--- a/base/trace_event/memory_tracing_observer.cc
+++ b/base/trace_event/memory_tracing_observer.cc
@@ -4,6 +4,7 @@
 
 #include "base/trace_event/memory_tracing_observer.h"
 
+#include "base/memory/ptr_util.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/trace_event_argument.h"
 
@@ -56,11 +57,15 @@ void MemoryTracingObserver::OnTraceLogEnabled() {
   const TraceConfig::MemoryDumpConfig& memory_dump_config =
       trace_config.memory_dump_config();
 
+  memory_dump_config_ =
+      MakeUnique<TraceConfig::MemoryDumpConfig>(memory_dump_config);
+
   memory_dump_manager_->Enable(memory_dump_config);
 }
 
 void MemoryTracingObserver::OnTraceLogDisabled() {
   memory_dump_manager_->Disable();
+  memory_dump_config_ = nullptr;

[Primiano Tucci (use gerrit), 2017/05/05 13:38:25]

.reset()? I thought you can't do this with unique_ptrs?

[hjd, 2017/05/05 14:50:53]

Done.

 }
 
 bool MemoryTracingObserver::AddDumpToTraceIfEnabled(
@@ -71,6 +76,10 @@ bool MemoryTracingObserver::AddDumpToTraceIfEnabled(
   // dump then ignoring the result.
   if (!IsMemoryInfraTracingEnabled())
     return false;
+  // If the dump mode is too detailed don't add to trace to avoid accidentally
+  // including PII.
+  if (!IsDumpModeAllowed(req_args->level_of_detail))
+    return false;
 
   CHECK_NE(MemoryDumpType::SUMMARY_ONLY, req_args->dump_type);
 
@@ -94,5 +103,12 @@ bool MemoryTracingObserver::AddDumpToTraceIfEnabled(
   return true;
 }
 
+bool MemoryTracingObserver::IsDumpModeAllowed(
+    MemoryDumpLevelOfDetail dump_mode) const {
+  if (memory_dump_config_ == nullptr)

[Primiano Tucci (use gerrit), 2017/05/05 13:38:25]

use the bool operator, i.e. if (!memory_dump_config_) . Ithink there was a
discussion about this on chromium-dev long time ago (I can't even recall the
rationale honestly, but I think that this was the TL;DR, maybe for code size?)

[hjd, 2017/05/05 14:50:53]

Done. I love that we use a static typed language where the compiler can remove
the cost of abstractions... 

+    return false;
+  return memory_dump_config_->allowed_dump_modes.count(dump_mode) != 0;
+}
+
 }  // namespace trace_event
 }  // namespace base