[ChromeDriver] Implementing tracing support

chrome/test/chromedriver/capabilities.h

 // Copyright (c) 2013 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.
 
 #ifndef CHROME_TEST_CHROMEDRIVER_CAPABILITIES_H_
 #define CHROME_TEST_CHROMEDRIVER_CAPABILITIES_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 61 matching lines @@
     kDefaultDisabled,
     kExplicitlyEnabled,
     kExplicitlyDisabled
   };
 
   InspectorDomainStatus network;
   InspectorDomainStatus page;
   InspectorDomainStatus timeline;
 
   std::string trace_categories;  // Non-empty string enables tracing.
+  int buffer_usage_reporting_interval;  // ms between trace buffer usage events.
 };
 
 struct Capabilities {
   Capabilities();
   ~Capabilities();
 
   // Return true if remote host:port session is to be used.
   bool IsRemoteBrowser() const;
 
   // Return true if android package is specified.
@@ skipping 44 matching lines @@
   std::string minidump_path;
 
   PerfLoggingPrefs perf_logging_prefs;
 
   scoped_ptr<base::DictionaryValue> prefs;
 
   Switches switches;
 };
 
 #endif  // CHROME_TEST_CHROMEDRIVER_CAPABILITIES_H_