Add UMA Histogram Manager to Cronet.

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

Index: components/cronet/android/java/src/org/chromium/net/HistogramManager.java
diff --git a/components/cronet/android/java/src/org/chromium/net/HistogramManager.java b/components/cronet/android/java/src/org/chromium/net/HistogramManager.java
new file mode 100644
index 0000000000000000000000000000000000000000..4995129765086358f69903bece9c128727e05326
--- /dev/null
+++ b/components/cronet/android/java/src/org/chromium/net/HistogramManager.java
@@ -0,0 +1,25 @@
+// 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 org.chromium.base.JNINamespace;
+
+/**
+ * Controls UMA histograms.
+ */
+@JNINamespace("cronet")
+public final class HistogramManager {
+    public HistogramManager() {
+    }
+
+    /**
+     * Get histogram deltas serialized as protobuf.

[Alexei Svitkine (slow), 2014/12/03 16:46:53]

Mention that it's the deltas since the last call.

+     */
+    public byte[] getHistogramDeltas() {
+        return nativeGetHistogramDeltas();
+    }
+
+    private native byte[] nativeGetHistogramDeltas();
+}