Add Tracing.getCategories to devtools_tracing_handler.cc.

content/browser/devtools/devtools_tracing_handler.h

Index: content/browser/devtools/devtools_tracing_handler.h
diff --git a/content/browser/devtools/devtools_tracing_handler.h b/content/browser/devtools/devtools_tracing_handler.h
index 787a123f666e57a708f7601bdaa86c4a2c5e4dd9..7c3b8e645e4bb6e8e6d52f8e7e412d6003fbc534 100644
--- a/content/browser/devtools/devtools_tracing_handler.h
+++ b/content/browser/devtools/devtools_tracing_handler.h
@@ -5,6 +5,9 @@
 #ifndef CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_TRACING_HANDLER_H_
 #define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_TRACING_HANDLER_H_
 
+#include <set>
+#include <string>
+
 #include "base/memory/weak_ptr.h"
 #include "content/browser/devtools/devtools_protocol.h"
 #include "content/public/browser/tracing_controller.h"
@@ -38,6 +41,11 @@ class DevToolsTracingHandler : public DevToolsProtocol::Handler {
   scoped_refptr<DevToolsProtocol::Response> OnEnd(
       scoped_refptr<DevToolsProtocol::Command> command);
 
+  scoped_refptr<DevToolsProtocol::Response> OnGetCategories(
+      scoped_refptr<DevToolsProtocol::Command> command);
+  void OnCategoriesReceived(scoped_refptr<DevToolsProtocol::Command> command,
+                            const std::set<std::string>& category_set);
+
   TracingController::Options TraceOptionsFromString(const std::string& options);
 
   void DisableRecording(