--- a/media/webrtc/signaling/src/common/browser_logging/WebRtcLog.cpp
+++ b/media/webrtc/signaling/src/common/browser_logging/WebRtcLog.cpp
@@ -56,22 +56,21 @@ private:
 
 // For WEBRTC_TRACE()
 static WebRtcTraceCallback gWebRtcCallback;
 // For LOG()
 static mozilla::StaticAutoPtr<LogSinkImpl> sSink;
 
 void
 GetWebRtcLogPrefs(uint32_t *aTraceMask, nsACString& aLogFile,
-                  nsACString& aAECLogDir, bool *aMultiLog)
+                  bool *aMultiLog)
 {
   *aMultiLog = mozilla::Preferences::GetBool("media.webrtc.debug.multi_log");
   *aTraceMask = mozilla::Preferences::GetUint("media.webrtc.debug.trace_mask");
   mozilla::Preferences::GetCString("media.webrtc.debug.log_file", aLogFile);
-  mozilla::Preferences::GetCString("media.webrtc.debug.aec_log_dir", aAECLogDir);
   webrtc::Trace::set_aec_debug_size(mozilla::Preferences::GetUint("media.webrtc.debug.aec_dump_max_size"));
 }
 
 mozilla::LogLevel
 CheckOverrides(uint32_t *aTraceMask, nsACString *aLogFile, bool *aMultiLog)
 {
   mozilla::LogModule *log_info = sWebRtcLog;
   mozilla::LogLevel log_level = log_info->Level();
@@ -118,17 +117,17 @@ CheckOverrides(uint32_t *aTraceMask, nsA
   const char *file_name = PR_GetEnv("WEBRTC_TRACE_FILE");
   if (file_name) {
     aLogFile->Assign(file_name);
   }
   return log_level;
 }
 
 void ConfigWebRtcLog(mozilla::LogLevel level, uint32_t trace_mask,
-                     nsCString &aLogFile, nsCString &aAECLogDir, bool multi_log)
+                     nsCString &aLogFile, bool multi_log)
 {
   if (gWebRtcTraceLoggingOn) {
     return;
   }
 
 #if defined(ANDROID)
   // Special case: use callback to pipe to NSPR logging.
   aLogFile.Assign(default_log_name);
@@ -212,99 +211,86 @@ void StartWebRtcLog(uint32_t log_level)
       webrtc::Trace::set_level_filter(webrtc::kTraceNone);
     }
     return;
   }
 
   uint32_t trace_mask = 0;
   bool multi_log = false;
   nsAutoCString log_file;
-  nsAutoCString aec_log_dir;
 
-  GetWebRtcLogPrefs(&trace_mask, log_file, aec_log_dir, &multi_log);
+  GetWebRtcLogPrefs(&trace_mask, log_file, &multi_log);
   mozilla::LogLevel level = CheckOverrides(&trace_mask, &log_file, &multi_log);
 
   if (trace_mask == 0) {
     trace_mask = log_level;
   }
 
-  ConfigWebRtcLog(level, trace_mask, log_file, aec_log_dir, multi_log);
+  ConfigWebRtcLog(level, trace_mask, log_file, multi_log);
 
 }
 
 void EnableWebRtcLog()
 {
   if (gWebRtcTraceLoggingOn) {
     return;
   }
 
   uint32_t trace_mask = 0;
   bool multi_log = false;
   nsAutoCString log_file;
-  nsAutoCString aec_log_dir;
 
-  GetWebRtcLogPrefs(&trace_mask, log_file, aec_log_dir, &multi_log);
+  GetWebRtcLogPrefs(&trace_mask, log_file, &multi_log);
   mozilla::LogLevel level = CheckOverrides(&trace_mask, &log_file, &multi_log);
-  ConfigWebRtcLog(level, trace_mask, log_file, aec_log_dir, multi_log);
+  ConfigWebRtcLog(level, trace_mask, log_file, multi_log);
 }
 
 // Called when we destroy the singletons from PeerConnectionCtx or if the
 // user changes logging in about:webrtc
 void StopWebRtcLog()
 {
   // TODO(NG) strip/fix gWebRtcTraceLoggingOn which is never set to true
   webrtc::Trace::set_level_filter(webrtc::kTraceNone);
   webrtc::Trace::SetTraceCallback(nullptr);
   webrtc::Trace::SetTraceFile(nullptr);
   if (sSink) {
     rtc::LogMessage::RemoveLogToStream(sSink);
     sSink = nullptr;
   }
 }
 
-void ConfigAecLog(nsCString &aAECLogDir) {
+void ConfigAecLog() {
   if (webrtc::Trace::aec_debug()) {
     return;
   }
+  nsCString aAECLogDir;
 #if defined(ANDROID)
-  // For AEC, do not use a default value: force the user to specify a directory.
-  if (aAECLogDir.IsEmpty()) {
-    aAECLogDir.Assign(default_tmp_dir);
-  }
+  aAECLogDir.Assign(default_tmp_dir);
 #else
-  if (aAECLogDir.IsEmpty()) {
-    nsCOMPtr<nsIFile> tempDir;
-    nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(tempDir));
-    if (NS_SUCCEEDED(rv)) {
-      if (aAECLogDir.IsEmpty()) {
-        tempDir->GetNativePath(aAECLogDir);
-      }
-    }
+  nsCOMPtr<nsIFile> tempDir;
+  nsresult rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(tempDir));
+  if (NS_SUCCEEDED(rv)) {
+    tempDir->GetNativePath(aAECLogDir);
   }
 #endif
   webrtc::Trace::set_aec_debug_filename(aAECLogDir.get());
-  if (XRE_IsParentProcess()) {
-    // Capture the final choice for the aec_log_dir setting.
-    mozilla::Preferences::SetCString("media.webrtc.debug.aec_log_dir", aAECLogDir);
-  }
 }
 
 void StartAecLog()
 {
   if (webrtc::Trace::aec_debug()) {
     return;
   }
   uint32_t trace_mask = 0;
   bool multi_log = false;
   nsAutoCString log_file;
-  nsAutoCString aec_log_dir;
 
-  GetWebRtcLogPrefs(&trace_mask, log_file, aec_log_dir, &multi_log);
+  GetWebRtcLogPrefs(&trace_mask, log_file, &multi_log);
   CheckOverrides(&trace_mask, &log_file, &multi_log);
-  ConfigAecLog(aec_log_dir);
+  ConfigAecLog();
 
   webrtc::Trace::set_aec_debug(true);
 }
 
 void StopAecLog()
 {
   webrtc::Trace::set_aec_debug(false);
 }

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -466,17 +466,16 @@ pref("media.navigator.video.use_remb", t
 pref("media.navigator.video.use_tmmbr", false);
 pref("media.navigator.audio.use_fec", true);
 pref("media.navigator.video.red_ulpfec_enabled", false);
 
 pref("media.peerconnection.dtmf.enabled", true);
 
 pref("media.webrtc.debug.trace_mask", 0);
 pref("media.webrtc.debug.multi_log", false);
-pref("media.webrtc.debug.aec_log_dir", "");
 pref("media.webrtc.debug.log_file", "");
 pref("media.webrtc.debug.aec_dump_max_size", 4194304); // 4MB
 
 pref("media.navigator.video.default_width",0);  // adaptive default
 pref("media.navigator.video.default_height",0); // adaptive default
 pref("media.peerconnection.enabled", true);
 pref("media.peerconnection.video.enabled", true);
 pref("media.navigator.video.max_fs", 12288); // Enough for 2048x1536