Reland of [tracing] Add native allocation tracing mode.

base/trace_event/heap_profiler_allocation_context_tracker_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.

[Primiano Tucci (use gerrit), 2016/04/28 07:02:42]

Would be nice to cover the code above (and the various corner cases) in this
unittest.
Let's do that in a separate CL after this sticks.
A good approach would be mocking at the base::debug::TraceStackFramePointers
level, by adding a mock_unwind_function_for_tests_ field.

 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 
 #include <iterator>
 
 #include "base/memory/ref_counted.h"
 #include "base/pending_task.h"
 #include "base/trace_event/heap_profiler.h"
@@ skipping 43 matching lines @@
           ->GetContextSnapshot();
 
   ASSERT_EQ(0u, ctx.backtrace.frame_count);
 }
 
 class AllocationContextTrackerTest : public testing::Test {
  public:
   void SetUp() override {
     TraceConfig config("");
     TraceLog::GetInstance()->SetEnabled(config, TraceLog::RECORDING_MODE);
-    AllocationContextTracker::SetCaptureEnabled(true);
+    AllocationContextTracker::SetCaptureMode(
+        AllocationContextTracker::CaptureMode::PSEUDO_STACK);
   }
 
   void TearDown() override {
-    AllocationContextTracker::SetCaptureEnabled(false);
+    AllocationContextTracker::SetCaptureMode(
+        AllocationContextTracker::CaptureMode::DISABLED);
     TraceLog::GetInstance()->SetDisabled();
   }
 };
 
 // Check that |TRACE_EVENT| macros push and pop to the pseudo stack correctly.
 TEST_F(AllocationContextTrackerTest, PseudoStackScopedTrace) {
   StackFrame c = StackFrame::FromTraceEventName(kCupcake);
   StackFrame d = StackFrame::FromTraceEventName(kDonut);
   StackFrame e = StackFrame::FromTraceEventName(kEclair);
   StackFrame f = StackFrame::FromTraceEventName(kFroyo);
@@ skipping 207 matching lines @@
       AllocationContextTracker::GetInstanceForCurrentThread()
           ->GetContextSnapshot();
   const StringPiece kTracingOverhead("tracing_overhead");
   ASSERT_EQ(kTracingOverhead,
             static_cast<const char*>(ctx.backtrace.frames[0].value));
   ASSERT_EQ(1u, ctx.backtrace.frame_count);
 }
 
 }  // namespace trace_event
 }  // namespace base