Update tracing framework to optionally use a ringbuffer.

content/browser/devtools/devtools_tracing_handler.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 "content/browser/devtools/devtools_tracing_handler.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/json/json_writer.h"
 #include "base/location.h"
 #include "base/values.h"
 #include "content/browser/devtools/devtools_http_handler_impl.h"
 #include "content/public/browser/trace_controller.h"
 #include "content/public/browser/trace_subscriber.h"
 
 namespace content {
 
 namespace {
 
 const char kTracingDomain[] = "Tracing";
 
 const char kTracingStartCommand[] = "Tracing.start";
 const char kTracingEndCommand[] = "Tracing.end";
 
 const char kTracingCompleteNotification[] = "Tracing.tracingComplete";
 const char kTracingDataCollected[] = "Tracing.dataCollected";
 
 const char kCategoriesParam[] = "categories";
+const char kContinuousTracing[] = "continuous_tracing";
 
 }  // namespace
 
 DevToolsTracingHandler::DevToolsTracingHandler()
     : DevToolsBrowserTarget::DomainHandler(kTracingDomain),
       is_running_(false) {
   RegisterCommandHandler(kTracingStartCommand,
                          base::Bind(&DevToolsTracingHandler::OnStart,
                                     base::Unretained(this)));
   RegisterCommandHandler(kTracingEndCommand,
@@ skipping 14 matching lines @@
   if (is_running_) {
     base::DictionaryValue* params = new base::DictionaryValue();
     params->SetString("value", trace_fragment->data());
     SendNotification(kTracingDataCollected, params);
   }
 }
 
 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);
 }
 
 
 scoped_ptr<DevToolsProtocol::Response>
 DevToolsTracingHandler::OnEnd(DevToolsProtocol::Command* command) {
   TraceController::GetInstance()->EndTracingAsync(this);
   return command->SuccessResponse(NULL);
 }
 
 }  // namespace content