Add method getAllHeaders to HttpUrlRequest.

components/cronet/android/java/src/org/chromium/net/HttpUrlConnectionUrlRequest.java

Index: components/cronet/android/java/src/org/chromium/net/HttpUrlConnectionUrlRequest.java
diff --git a/components/cronet/android/java/src/org/chromium/net/HttpUrlConnectionUrlRequest.java b/components/cronet/android/java/src/org/chromium/net/HttpUrlConnectionUrlRequest.java
index 33c940cbd682e0ffdc81efd686edb98845f25a76..2bae9434dd6107c64a896bfc20f9bc7a9a1b1fe2 100644
--- a/components/cronet/android/java/src/org/chromium/net/HttpUrlConnectionUrlRequest.java
+++ b/components/cronet/android/java/src/org/chromium/net/HttpUrlConnectionUrlRequest.java
@@ -476,7 +476,6 @@ class HttpUrlConnectionUrlRequest implements HttpUrlRequest {
         return mContentType;
     }
 
-
     @Override
     public String getHeader(String name) {
         if (mConnection == null) {
@@ -492,6 +491,14 @@ class HttpUrlConnectionUrlRequest implements HttpUrlRequest {
         return null;
     }
 
+    @Override
+    public Map<String, List<String>> getAllHeaders() {
+        if (mConnection == null) {
+            throw new IllegalStateException("Response headers not available");
+        }
+        return mConnection.getHeaderFields();
+    }
+
     private void validateNotStarted() {
         if (mStarted) {
             throw new IllegalStateException("Request already started");