Add HttpUrlConnection backed implementation of CronetEngine.

components/cronet/android/api/src/org/chromium/net/UrlResponseInfo.java

Index: components/cronet/android/api/src/org/chromium/net/UrlResponseInfo.java
diff --git a/components/cronet/android/api/src/org/chromium/net/UrlResponseInfo.java b/components/cronet/android/api/src/org/chromium/net/UrlResponseInfo.java
index b8f407e22ffa217a9565c99ad4c80c07e1fb3513..f9461d95dee42463d78bb622bb62b7d44673ba15 100644
--- a/components/cronet/android/api/src/org/chromium/net/UrlResponseInfo.java
+++ b/components/cronet/android/api/src/org/chromium/net/UrlResponseInfo.java
@@ -61,8 +61,7 @@ public final class UrlResponseInfo {
             if (mHeadersMap != null) {
                 return mHeadersMap;
             }
-            Map<String, List<String>> map =
-                    new TreeMap<String, List<String>>(String.CASE_INSENSITIVE_ORDER);
+            Map<String, List<String>> map = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
             for (Map.Entry<String, String> entry : mAllHeadersList) {
                 List<String> values = new ArrayList<String>();
                 if (map.containsKey(entry.getKey())) {
@@ -205,10 +204,12 @@ public final class UrlResponseInfo {
 
     @Override
     public String toString() {
-        return String.format(Locale.ROOT, "UrlResponseInfo[%s]: urlChain = %s, "
+        return String.format(Locale.ROOT, "UrlResponseInfo@[%s][%s]: urlChain = %s, "
                         + "httpStatus = %d %s, headers = %s, wasCached = %b, "
                         + "negotiatedProtocol = %s, proxyServer= %s, receivedBytesCount = %d",
-                getUrl(), getUrlChain().toString(), getHttpStatusCode(), getHttpStatusText(),
+                // Prevent asserting on the contents of this string

[pauljensen, 2015/12/21 20:27:58]

I don't understand this comment.  How does adding code here cause an assert on
the contents of this string?

[Charles, 2015/12/21 23:36:25]

This is a common pattern in java - including the identity hashcode of the object
(which is derived from its memory address) means that the toString() of this
object is different for each object instance, and is unpredictable. It prevents
people from writing the types of brittle tests that I replaced in this CL, which
compare an object to a string literal. 

[pauljensen, 2015/12/29 16:35:53]

Acknowledged.

+                Integer.toHexString(System.identityHashCode(this)), getUrl(),
+                getUrlChain().toString(), getHttpStatusCode(), getHttpStatusText(),
                 getAllHeadersAsList().toString(), wasCached(), getNegotiatedProtocol(),
                 getProxyServer(), getReceivedBytesCount());
     }