Measure time spent during StrictMode violations.

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappAuthenticator.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappAuthenticator.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappAuthenticator.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappAuthenticator.java
index 833fd5da2276c697622200720b093e29e5d9693a..c8297705dcb749685c074876ae937d75ccce7f86 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappAuthenticator.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappAuthenticator.java
@@ -8,9 +8,11 @@ import android.annotation.SuppressLint;
 import android.content.Context;
 import android.os.AsyncTask;
 import android.os.StrictMode;
+import android.os.SystemClock;
 import android.util.Log;
 
 import org.chromium.base.SecureRandomInitializer;
+import org.chromium.base.metrics.RecordHistogram;
 
 import java.io.File;
 import java.io.FileInputStream;
@@ -21,6 +23,7 @@ import java.security.SecureRandom;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.FutureTask;
+import java.util.concurrent.TimeUnit;
 
 import javax.crypto.KeyGenerator;
 import javax.crypto.Mac;
@@ -59,7 +62,10 @@ public class WebappAuthenticator {
         // Temporarily allowing disk access while fixing. TODO: http://crbug.com/525785
         StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
         try {
+            long time = SystemClock.elapsedRealtime();
             goodMac = getMacForUrl(context, url);
+            RecordHistogram.recordTimesHistogram("Android.StrictMode.WebappAuthenticatorMac",
+                    SystemClock.elapsedRealtime() - time, TimeUnit.MILLISECONDS);
         } finally {
             StrictMode.setThreadPolicy(oldPolicy);
         }