Add option to enable sampler.

base/debug/trace_event_impl.cc

 // Copyright (c) 2012 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/debug/trace_event_impl.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/debug/leak_annotations.h"
@@ skipping 71 matching lines @@
 int g_category_index = g_num_builtin_categories; // Skip default categories.
 
 // The name of the current thread. This is used to decide if the current
 // thread name has changed. We combine all the seen thread names into the
 // output name for the thread.
 LazyInstance<ThreadLocalPointer<const char> >::Leaky
     g_current_thread_name = LAZY_INSTANCE_INITIALIZER;
 
 const char kRecordUntilFull[] = "record-until-full";
 const char kRecordContinuously[] = "record-continuously";
+const char kEnableSampling[] = "enable-sampling";
 
 size_t NextIndex(size_t index) {
   index++;
   if (index >= kTraceEventBufferSize)
     index = 0;
   return index;
 }
 
 }  // namespace
 
@@ skipping 652 matching lines @@
   std::vector<std::string> split;
   base::SplitString(options, ',', &split);
   int ret = 0;
   for (std::vector<std::string>::iterator iter = split.begin();
        iter != split.end();
        ++iter) {
     if (*iter == kRecordUntilFull) {
       ret |= RECORD_UNTIL_FULL;
     } else if (*iter == kRecordContinuously) {
       ret |= RECORD_CONTINUOUSLY;
+    } else if (*iter == kEnableSampling) {
+      ret |= ENABLE_SAMPLING;
     } else {
       NOTREACHED();  // Unknown option provided.
     }
   }
   if (!(ret & RECORD_UNTIL_FULL) && !(ret & RECORD_CONTINUOUSLY))
     ret |= RECORD_UNTIL_FULL;  // Default when no options are specified.
 
   return static_cast<Options>(ret);
 }
 
@@ skipping 772 matching lines @@
         0,                       // num_args
         NULL,                    // arg_names
         NULL,                    // arg_types
         NULL,                    // arg_values
         NULL,                    // convertable values
         TRACE_EVENT_FLAG_NONE);  // flags
   }
 }
 
 }  // namespace trace_event_internal