Add a mode flag to the tracing framework.

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..c33002c8fe8c1bb26a1843f43170a9e2239e0bfb 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 kTraceModeParam[] = "trace-mode";
 
 }  // namespace
 
@@ -63,7 +64,15 @@ DevToolsTracingHandler::OnStart(DevToolsProtocol::Command* command) {
   base::DictionaryValue* params = command->params();
   if (params && params->HasKey(kCategoriesParam))
     params->GetString(kCategoriesParam, &categories);
-  TraceController::GetInstance()->BeginTracing(this, categories);
+
+  base::debug::TraceMode mode = base::debug::UNTIL_FULL;
+  if (params && params->HasKey(kTraceModeParam)) {
+    int mode_;
+    params->GetInteger(kTraceModeParam, &mode_);

[pfeldman, 2013/02/20 09:33:38]

You should check for it returning value here.
We also use symbolic names (string enums) for flags like this. You would end up
with switch here, but the protocol will get more stable.

[dsinclair, 2013/02/20 20:36:13]

Done.

I put the conversion in the trace_event_impl.cc code as I've used the same
string names coming from the trace_ui code.

+    mode = static_cast<base::debug::TraceMode>(mode_);
+  }
+
+  TraceController::GetInstance()->BeginTracing(this, categories, mode);
   is_running_ = true;
   return command->SuccessResponse(NULL);
 }