Buffer UI navigation events in DataUseTabModel until rule fetch

chrome/android/java/src/org/chromium/chrome/browser/datausage/ExternalDataUseObserver.java

Index: chrome/android/java/src/org/chromium/chrome/browser/datausage/ExternalDataUseObserver.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/datausage/ExternalDataUseObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/datausage/ExternalDataUseObserver.java
index ce04c27e4abf1d7b8482076d064a96081c5cfe90..26f8dd07f976f6a9d6d7f3266f5812c05f56e08c 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/datausage/ExternalDataUseObserver.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/datausage/ExternalDataUseObserver.java
@@ -112,9 +112,10 @@ public class ExternalDataUseObserver {
     }
 
     /**
-    * Fetches matching rules and returns them via {@link #fetchMatchingRulesDone}. While the
-    * fetch is underway, it is illegal to make calls to this method.
-    */
+     * Fetches matching rules and returns them via {@link #fetchMatchingRulesDone}. subsequent
+     * calls to this method While the fetch is underway, may cause the {@link
+     * #fetchMatchingRulesDone} callback to be missed for the subsequent call.
+     */
     @CalledByNative
     protected void fetchMatchingRules() {
         fetchMatchingRulesDone(null, null, null);