Change the parameters of calculating maximum decode time.

- Reduce the window size from 20 to 10 seconds. If there is
  any spurious high decode time, it will be faster to pass it.
- Ignore more samples at first because HW decoder has higher
  initialization latency.

BUG=crbug.com/298176
TEST=Run apprtc loopback on Chromebook Daisy.
R=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2315005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4874 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/video_coding/main/source/codec_timer.h

@@ -18,7 +18,7 @@ namespace webrtc
 {
 
 // MAX_HISTORY_SIZE * SHORT_FILTER_MS defines the window size in milliseconds
-#define MAX_HISTORY_SIZE 20
+#define MAX_HISTORY_SIZE 10
 #define SHORT_FILTER_MS 1000
 
 class VCMShortMaxSample
@@ -50,9 +50,10 @@ private:
     void ProcessHistory(int64_t nowMs);
 
     int32_t                     _filteredMax;
-    bool                              _firstDecodeTime;
+    // The number of samples ignored so far.
+    int32_t                     _ignoredSampleCount;
     int32_t                     _shortMax;
-    VCMShortMaxSample                 _history[MAX_HISTORY_SIZE];
+    VCMShortMaxSample           _history[MAX_HISTORY_SIZE];
 
 };