Update tracing framework to optionally use a ringbuffer.

content/browser/devtools/devtools_tracing_handler.cc

Index: content/browser/devtools/devtools_tracing_handler.cc
diff --git a/content/browser/devtools/devtools_tracing_handler.cc b/content/browser/devtools/devtools_tracing_handler.cc
index e16768f6dc8c8b2ad00a9c11e5414969fb965c2b..bb7087b222d2e39f99e77c616fe6a4d61f2aae14 100644
--- a/content/browser/devtools/devtools_tracing_handler.cc
+++ b/content/browser/devtools/devtools_tracing_handler.cc
@@ -26,6 +26,7 @@ const char kTracingCompleteNotification[] = "Tracing.tracingComplete";
 const char kTracingDataCollected[] = "Tracing.dataCollected";
 
 const char kCategoriesParam[] = "categories";
+const char kContinuousTracing[] = "continuous_tracing";
 
 }  // namespace
 
@@ -60,10 +61,14 @@ void DevToolsTracingHandler::OnTraceDataCollected(
 scoped_ptr<DevToolsProtocol::Response>
 DevToolsTracingHandler::OnStart(DevToolsProtocol::Command* command) {
   std::string categories;
+  bool continuous_tracing = false;
   base::DictionaryValue* params = command->params();
   if (params && params->HasKey(kCategoriesParam))
     params->GetString(kCategoriesParam, &categories);
-  TraceController::GetInstance()->BeginTracing(this, categories);
+  if (params && params->HasKey(kContinuousTracing))
+    params->GetBoolean(kContinuousTracing, &continuous_tracing);
+  TraceController::GetInstance()->BeginTracing(this, categories,
+                                               continuous_tracing);
   is_running_ = true;
   return command->SuccessResponse(NULL);
 }