Cronet Java wrappers to fallback to HttpUrlConnection if Cronet is not available.

net/cronet/android/java/src/org/chromium/net/UserAgent.java

Index: net/cronet/android/java/src/org/chromium/net/UserAgent.java
diff --git a/net/cronet/android/java/src/org/chromium/net/UserAgent.java b/net/cronet/android/java/src/org/chromium/net/UserAgent.java
new file mode 100644
index 0000000000000000000000000000000000000000..77febd5782c33efe7550c95c5c02c1712aa2e804
--- /dev/null
+++ b/net/cronet/android/java/src/org/chromium/net/UserAgent.java
@@ -0,0 +1,74 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.net;
+
+import android.content.Context;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.os.Build;
+
+import java.util.Locale;
+
+/**
+ * Constructs a User-Agent string.
+ */
+public final class UserAgent {
+    private static final Object sLock = new Object();
+
+    private static int sVersionCode;
+
+    private UserAgent() {
+    }
+
+    public static String from(Context context) {
+        StringBuilder builder = new StringBuilder();
+
+        // Our package name and version.
+        builder.append(context.getPackageName());
+        builder.append('/');
+        builder.append(versionFromContext(context));
+
+        // The platform version.
+        builder.append(" (Linux; U; Android ");
+        builder.append(Build.VERSION.RELEASE);
+        builder.append("; ");
+        builder.append(Locale.getDefault().toString());
+
+        String model = Build.MODEL;
+        if (model.length() > 0) {
+            builder.append("; ");
+            builder.append(model);
+        }
+
+        String id = Build.ID;
+        if (id.length() > 0) {
+            builder.append("; Build/");
+            builder.append(id);
+        }
+
+        builder.append(')');
+
+        return builder.toString();
+    }
+
+    private static int versionFromContext(Context context) {
+        synchronized (sLock) {
+            if (sVersionCode == 0) {
+                PackageManager packageManager = context.getPackageManager();
+                String packageName = context.getPackageName();
+                try {
+                    PackageInfo packageInfo = packageManager.getPackageInfo(
+                            packageName, 0);
+                    sVersionCode = packageInfo.versionCode;
+                } catch (NameNotFoundException e) {
+                    throw new IllegalStateException(
+                            "Cannot determine package version");
+                }
+            }
+            return sVersionCode;
+        }
+    }
+}