Implement timing metrics for UrlRequest

components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java

Index: components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
diff --git a/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java b/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
index f9656fac1bc069dfd4df2271014bfbf926d1c898..d5f5259c7aba2039d7c58472769a924a379db581 100644
--- a/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
+++ b/components/cronet/android/java/src/org/chromium/net/impl/CronetUrlRequestContext.java
@@ -82,7 +82,8 @@ public class CronetUrlRequestContext extends CronetEngine {
 
     /**
      * Locks operations on the list of RequestFinishedInfo.Listeners, because operations can happen
-     * on any thread.
+     * on any thread. This should be used for fine-grained locking only. In particular, don't call
+     * any UrlRequest methods that acquire mUrlRequestAdapterLock while holding this lock.
      */
     private final Object mFinishedListenerLock = new Object();
 
@@ -430,6 +431,12 @@ public class CronetUrlRequestContext extends CronetEngine {
         }
     }
 
+    boolean hasRequestFinishedListener() {
+        synchronized (mFinishedListenerLock) {
+            return !mFinishedListenerList.isEmpty();
+        }
+    }
+
     @Override
     public URLConnection openConnection(URL url) {
         return openConnection(url, Proxy.NO_PROXY);