Add UMA for signin through NTP content suggestions.

base/android/java/src/org/chromium/base/metrics/RecordUserAction.java

Index: base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
diff --git a/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java b/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
index 06004d69597630759b1f533a9ff09467d9ed51df..18a4f4dd9ce91574a9e17b05be51324ca0a2280b 100644
--- a/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
+++ b/base/android/java/src/org/chromium/base/metrics/RecordUserAction.java
@@ -5,6 +5,7 @@
 package org.chromium.base.metrics;
 
 import org.chromium.base.ThreadUtils;
+import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.JNINamespace;
 
 /**
@@ -18,7 +19,19 @@ import org.chromium.base.annotations.JNINamespace;
  */
 @JNINamespace("base::android")
 public class RecordUserAction {
+    private static boolean sIsDisabledForTests = false;
+
+    /**
+     * Tests may not have native initialized, so they may need to disable metrics.
+     */
+    @VisibleForTesting
+    public static void disableForTests() {
+        sIsDisabledForTests = true;
+    }
+
     public static void record(final String action) {
+        if (sIsDisabledForTests) return;
+
         if (ThreadUtils.runningOnUiThread()) {
             nativeRecordUserAction(action);
             return;