DevTools: handle Tracing.start in both browser and renderer

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 5e97b1b69343cf4c83967507b6d678948869ea64..b20c146eb87b28c8d191b555d484e4d1d188c0e9 100644
--- a/content/browser/devtools/devtools_tracing_handler.cc
+++ b/content/browser/devtools/devtools_tracing_handler.cc
@@ -46,8 +46,9 @@ void ReadFile(
 
 }  // namespace
 
-DevToolsTracingHandler::DevToolsTracingHandler()
-    : weak_factory_(this) {
+DevToolsTracingHandler::DevToolsTracingHandler(
+    DevToolsTracingHandler::Target target)
+    : weak_factory_(this), target_(target) {
   RegisterCommandHandler(devtools::Tracing::start::kName,
                          base::Bind(&DevToolsTracingHandler::OnStart,
                                     base::Unretained(this)));
@@ -168,6 +169,14 @@ DevToolsTracingHandler::OnStart(
     }
   }
 
+  // If inspected target is a render process Tracing.start will be handled by
+  // tracing agent in the renderer.
+  if (target_ == Renderer) {
+    TracingController::GetInstance()->EnableRecording(
+        categories, options, TracingController::EnableRecordingDoneCallback());
+    return NULL;
+  }
+
   TracingController::GetInstance()->EnableRecording(
       categories, options,
       base::Bind(&DevToolsTracingHandler::OnTracingStarted,