[tracing] Allow enabling heap profiling from chrome://flags

base/trace_event/memory_dump_manager.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/trace_event/memory_dump_manager.h"
 
 #include <inttypes.h>
 #include <stdio.h>
 
 #include <algorithm>
@@ skipping 192 matching lines @@
   if (heap_profiling_enabled_)
     return;
 
   if (!CommandLine::InitializedForCurrentProcess() ||
       !CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableHeapProfiling))
     return;
 
   std::string profiling_mode = CommandLine::ForCurrentProcess()
       ->GetSwitchValueASCII(switches::kEnableHeapProfiling);
-  if (profiling_mode == "") {
+  if (profiling_mode == switches::kEnableHeapProfilingModePseudo) {
     AllocationContextTracker::SetCaptureMode(
         AllocationContextTracker::CaptureMode::PSEUDO_STACK);
 #if !defined(OS_NACL)
   } else if (profiling_mode == switches::kEnableHeapProfilingModeNative) {
     // If we don't have frame pointers then native tracing falls-back to
     // using base::debug::StackTrace, which may be slow.
     AllocationContextTracker::SetCaptureMode(
         AllocationContextTracker::CaptureMode::NATIVE_STACK);
 #endif  // !defined(OS_NACL)
 #if BUILDFLAG(ENABLE_MEMORY_TASK_PROFILER)
@@ skipping 717 matching lines @@
   if (iter == process_dumps.end()) {
     std::unique_ptr<ProcessMemoryDump> new_pmd(
         new ProcessMemoryDump(session_state, dump_args));
     iter = process_dumps.insert(std::make_pair(pid, std::move(new_pmd))).first;
   }
   return iter->second.get();
 }
 
 }  // namespace trace_event
 }  // namespace base