Add a Java API for UMA histograms.

base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java

Index: base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java
diff --git a/base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java b/base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..82c1ca9b98d8deee0ecd9721f52b4be26b91418f
--- /dev/null
+++ b/base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java
@@ -0,0 +1,78 @@
+// 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.base.metrics;
+
+import android.test.InstrumentationTestCase;
+import android.test.suitebuilder.annotation.SmallTest;
+
+import org.chromium.base.library_loader.LibraryLoader;
+import org.chromium.base.test.util.MetricsUtils.HistogramDelta;
+
+/**
+ * Tests for the Java API for recording UMA histograms.
+ */
+public class RecordHistogramTest extends InstrumentationTestCase {
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+        LibraryLoader.ensureInitialized();
+        RecordHistogram.initialize();
+    }
+
+    /**
+     * Tests recording of boolean histograms.
+     */
+    @SmallTest
+    public void testRecordBooleanHistogram() {
+        String histogram = "HelloWorld.BooleanMetric";
+        HistogramDelta falseCount = new HistogramDelta(histogram, 0);
+        HistogramDelta trueCount = new HistogramDelta(histogram, 1);
+        assertEquals(0, trueCount.getDelta());
+        assertEquals(0, falseCount.getDelta());
+
+        RecordHistogram.recordBooleanHistogram(histogram, true);
+        assertEquals(1, trueCount.getDelta());
+        assertEquals(0, falseCount.getDelta());
+
+        RecordHistogram.recordBooleanHistogram(histogram, true);
+        assertEquals(2, trueCount.getDelta());
+        assertEquals(0, falseCount.getDelta());
+
+        RecordHistogram.recordBooleanHistogram(histogram, false);
+        assertEquals(2, trueCount.getDelta());
+        assertEquals(1, falseCount.getDelta());
+    }
+
+    /**
+     * Tests recording of enumerated histograms.
+     */
+    @SmallTest
+    public void testRecordEnumeratedHistogram() {
+        String histogram = "HelloWorld.EnumeratedMetric";
+        HistogramDelta zeroCount = new HistogramDelta(histogram, 0);
+        HistogramDelta oneCount = new HistogramDelta(histogram, 1);
+        HistogramDelta twoCount = new HistogramDelta(histogram, 2);
+        final int boundary = 3;
+
+        assertEquals(0, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(0, twoCount.getDelta());
+
+        RecordHistogram.recordEnumeratedHistogram(histogram, 0, boundary);
+        assertEquals(1, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(0, twoCount.getDelta());
+
+        RecordHistogram.recordEnumeratedHistogram(histogram, 0, boundary);
+        assertEquals(2, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(0, twoCount.getDelta());
+
+        RecordHistogram.recordEnumeratedHistogram(histogram, 2, boundary);
+        assertEquals(2, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(1, twoCount.getDelta());
+    }
+}