Measure time spent in SharedPrefs-loading StrictMode violations.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/ActivityAssigner.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/ActivityAssigner.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ActivityAssigner.java
index a05bdf7f0836052b7d3454f7e7d6e2749e6a6ef7..c01923984a7ed61d439d20aa2a7c4520ad5416ea 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/ActivityAssigner.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ActivityAssigner.java
@@ -6,15 +6,18 @@ package org.chromium.chrome.browser.webapps;
 
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.os.SystemClock;
 import android.util.Log;
 
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
+import org.chromium.base.metrics.RecordHistogram;
 
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Manages a rotating LRU buffer of WebappActivities to assign webapps to.
@@ -214,7 +217,14 @@ public class ActivityAssigner {
         // been corrupted somehow, just discard the whole map.
         SharedPreferences prefs = mContext.getSharedPreferences(PREF_PACKAGE, Context.MODE_PRIVATE);
         try {
+            long time = SystemClock.elapsedRealtime();
             final int numSavedEntries = prefs.getInt(PREF_NUM_SAVED_ENTRIES, 0);
+            try {
+                RecordHistogram.recordTimesHistogram("Android.StrictMode.WebappSharedPrefs",
+                        SystemClock.elapsedRealtime() - time, TimeUnit.MILLISECONDS);
+            } catch (UnsatisfiedLinkError error) {
+                // Intentionally ignored - it's ok to miss recording the metric occasionally.
+            }
             if (numSavedEntries <= NUM_WEBAPP_ACTIVITIES) {
                 for (int i = 0; i < numSavedEntries; ++i) {
                     String currentActivityIndexPref = PREF_ACTIVITY_INDEX + i;