Display pace in mm:second format.

MyTracks/res/values/strings.xml

@@ -1974,7 +1974,7 @@ limitations under the License.
   </string>
   <string name="settings_stats_rate_title"
     translation_description="In the 'Stats' settings, the option to change the preferred rate,
-      either speed (mi/hr) or pace (hr/mi).
+      either speed (mi/hr) or pace (min/mi).
 
       Character limit: ~23 (1 line)">
     Preferred rate
@@ -2131,7 +2131,7 @@ limitations under the License.
     Moving time
   </string>
   <string name="stats_pace"
-    translation_description="In the 'Stats' page, the pace like hours per mile.
+    translation_description="In the 'Stats' page, the pace like minutes per mile.
 
       Character limit: ~23 (1 line)">
     Pace

MyTracks/src/com/google/android/apps/mytracks/content/DescriptionGeneratorImpl.java

@@ -219,6 +219,15 @@ public class DescriptionGeneratorImpl implements DescriptionGenerator {
   void writePace(double speed, StringBuilder builder, int resId, String lineBreak) {
     String[] paceInMetrics = StringUtils.getSpeedParts(context, speed, true, false);
     String[] paceInImperial = StringUtils.getSpeedParts(context, speed, false, false);
+
+    if (paceInMetrics[0] == null) {
+      paceInMetrics[0] = context.getString(R.string.value_unknown);
+    }
+
+    if (paceInImperial[0] == null) {
+      paceInImperial[0] = context.getString(R.string.value_unknown);
+    }
+
     builder.append(context.getString(resId, paceInMetrics[0], paceInImperial[0]));
     builder.append(lineBreak);
   }

MyTracks/src/com/google/android/apps/mytracks/util/StringUtils.java

@@ -213,19 +213,18 @@ public class StringUtils {
       return result;
     }
     speed *= UnitConversions.MS_TO_KMH;
-    if (metricUnits) {
-      if (!reportSpeed) {
-        // convert from hours to minutes
-        speed = speed == 0 ? 0.0 : 60.0 / speed;
-      }
-    } else {
+    if (!metricUnits) {
       speed *= UnitConversions.KM_TO_MI;
-      if (!reportSpeed) {
-        // convert from hours to minutes
-        speed = speed == 0 ? 0.0 : 60.0 / speed;
-      }
     }
-    result[0] = String.format("%.2f", speed);
+    if (reportSpeed) {
+      result[0] = String.format("%.2f", speed);
+    } else {
+      // convert from hours to minutes
+      double pace = speed == 0 ? 0.0 : 60.0 / speed;
+      int minutes = (int) pace;
+      int seconds = (int) Math.round((pace - minutes) * 60.0);
+      result[0] = String.format("%d:%02d", minutes, seconds);  
+    }
     return result;
   }