Change minimum DTMF event duration to be 40 milliseconds

webrtc/pc/dtmfsender.cc

Index: webrtc/pc/dtmfsender.cc
diff --git a/webrtc/pc/dtmfsender.cc b/webrtc/pc/dtmfsender.cc
index bbb100ea61789d3b295170131793af258c8ec3cb..a08a53ce0e59dbd4a2ede5c4e3574a5338d6e245 100644
--- a/webrtc/pc/dtmfsender.cc
+++ b/webrtc/pc/dtmfsender.cc
@@ -39,10 +39,10 @@ static const int kDtmfCodeTwoSecondDelay = -1;
 static const int kDtmfTwoSecondInMs = 2000;
 static const char kDtmfValidTones[] = ",0123456789*#ABCDabcd";
 static const char kDtmfTonesTable[] = ",0123456789*#ABCD";
-// The duration cannot be more than 6000ms or less than 70ms. The gap between
+// The duration cannot be more than 6000ms or less than 40ms. The gap between
 // tones must be at least 50 ms.
 static const int kDtmfDefaultDurationMs = 100;
-static const int kDtmfMinDurationMs = 70;
+static const int kDtmfMinDurationMs = 40;
 static const int kDtmfMaxDurationMs = 6000;
 static const int kDtmfDefaultGapMs = 50;
 static const int kDtmfMinGapMs = 50;