Update tracing framework to optionally use a ringbuffer.

content/browser/tracing/trace_controller_impl.cc

Index: content/browser/tracing/trace_controller_impl.cc
diff --git a/content/browser/tracing/trace_controller_impl.cc b/content/browser/tracing/trace_controller_impl.cc
index 40a3f56d92195c13c25468c259ba140839698d18..3ad8a3422e86a8bf12a3ab54f3b79e7017794891 100644
--- a/content/browser/tracing/trace_controller_impl.cc
+++ b/content/browser/tracing/trace_controller_impl.cc
@@ -137,6 +137,12 @@ bool TraceControllerImpl::BeginTracing(
 
 bool TraceControllerImpl::BeginTracing(TraceSubscriber* subscriber,
                                        const std::string& categories) {
+  return BeginTracing(subscriber, categories, false);
+}
+
+bool TraceControllerImpl::BeginTracing(TraceSubscriber* subscriber,
+                                       const std::string& categories,
+                                       bool continuous_tracing) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!can_begin_tracing(subscriber))
@@ -144,6 +150,7 @@ bool TraceControllerImpl::BeginTracing(TraceSubscriber* subscriber,
 
   // Enable tracing
   TraceLog::GetInstance()->SetEnabled(categories);
+  TraceLog::GetInstance()->SetContinuousTracing(continuous_tracing);
 
   OnTracingBegan(subscriber);
 
@@ -261,7 +268,8 @@ void TraceControllerImpl::AddFilter(TraceMessageFilter* filter) {
 
   filters_.insert(filter);
   if (is_tracing_enabled()) {
-    filter->SendBeginTracing(included_categories_, excluded_categories_);
+    filter->SendBeginTracing(included_categories_, excluded_categories_,
+                             continuous_tracing_);
     if (!watch_category_.empty())
       filter->SendSetWatchEvent(watch_category_, watch_name_);
   }
@@ -285,9 +293,12 @@ void TraceControllerImpl::OnTracingBegan(TraceSubscriber* subscriber) {
 
   TraceLog::GetInstance()->GetEnabledTraceCategories(&included_categories_,
                                                      &excluded_categories_);
+  continuous_tracing_ = TraceLog::GetInstance()->GetContinuousTracing();
+
   // Notify all child processes.
   for (FilterMap::iterator it = filters_.begin(); it != filters_.end(); ++it) {
-    it->get()->SendBeginTracing(included_categories_, excluded_categories_);
+    it->get()->SendBeginTracing(included_categories_, excluded_categories_,
+                                continuous_tracing_);
   }
 }