Test field trial group with startswith rather than equals.

webrtc/system_wrappers/source/field_trial_default.cc

Index: webrtc/system_wrappers/source/field_trial_default.cc
diff --git a/webrtc/system_wrappers/source/field_trial_default.cc b/webrtc/system_wrappers/source/field_trial_default.cc
index 0e2c286117a1a2cc96687c61b5f6c2483b0e4c37..e5ed2476ab365f62967db41296f92fed833a026e 100644
--- a/webrtc/system_wrappers/source/field_trial_default.cc
+++ b/webrtc/system_wrappers/source/field_trial_default.cc
@@ -53,6 +53,10 @@ std::string FindFullName(const std::string& name) {
   return std::string();
 }
 
+bool IsEnabled(const char* name) {
+  return FindFullName(name).find("Enabled") == 0;
+}
+
 // Optionally initialize field trial from a string.
 void InitFieldTrialsFromString(const char* trials_string) {
   trials_init_string = trials_string;