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

chrome/browser/flag_descriptions.cc

 // Copyright 2017 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 "chrome/browser/flag_descriptions.h"
 
 namespace flag_descriptions {
 
 //  Material Design version of chrome://bookmarks
 
@@ skipping 3040 matching lines @@
     "User gesture is required for cross-origin iframes.";
 
 const char kOmniboxDisplayTitleForCurrentUrlName[] =
     "Include title for the current URL in the omnibox";
 
 const char kOmniboxDisplayTitleForCurrentUrlDescription[] =
     "In the event that the omnibox provides suggestions on-focus, the URL of "
     "the current page is provided as the first suggestion without a title. "
     "Enabling this flag causes the title to be displayed.";
 
+const char kEnableHeapProfilingName[] = "Heap profiling";
+
+const char kEnableHeapProfilingDescription[] = "Enables heap profiling.";
+
+const char kEnableHeapProfilingModePseudo[] = "Enabled (pseudo mode)";
+
+const char kEnableHeapProfilingModeNative[] = "Enabled (native mode)";
+
+const char kEnableHeapProfilingTaskProfiler[] = "Enabled (task mode)";
+
 }  // namespace flag_descriptions