Add count histograms to RecordHistogram.

This adds the Java equivalent of the following C++ macro:
UMA_HISTOGRAM_COUNTS.

BUG=442300,463125

Review URL: https://codereview.chromium.org/1004763003

Cr-Commit-Position: refs/heads/master@{#320388}

3 files changed, 89 insertions, 0 deletions

diff --git a/base/android/java/src/org/chromium/base/metrics/RecordHistogram.java b/base/android/java/src/org/chromium/base/metrics/RecordHistogram.java
index 08c314f..c1f6d36 100644
--- a/base/android/java/src/org/chromium/base/metrics/RecordHistogram.java
+++ b/base/android/java/src/org/chromium/base/metrics/RecordHistogram.java
@@ -43,6 +43,16 @@ public class RecordHistogram {
     }
 
     /**
+     * Records a sample in a count histogram of the given name. This is the Java equivalent of the
+     * UMA_HISTOGRAM_COUNTS C++ macro.
+     * @param name name of the histogram
+     * @param sample sample to be recorded, at least 1 and at most 999999
+     */
+    public static void recordCountHistogram(String name, int sample) {
+        nativeRecordCountHistogram(name, System.identityHashCode(name), sample);
+    }
+
+    /**
      * Records a sample in a histogram of times. Useful for recording short durations. This is the
      * Java equivalent of the UMA_HISTOGRAM_TIMES C++ macro.
      * @param name name of the histogram
@@ -123,6 +133,7 @@ public class RecordHistogram {
     private static native void nativeRecordBooleanHistogram(String name, int key, boolean sample);
     private static native void nativeRecordEnumeratedHistogram(
             String name, int key, int sample, int boundary);
+    private static native void nativeRecordCountHistogram(String name, int key, int sample);
 
     private static native int nativeGetHistogramValueCountForTesting(String name, int sample);
     private static native void nativeInitialize();
diff --git a/base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java b/base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java
index f0489d3..24af056 100644
--- a/base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java
+++ b/base/android/javatests/src/org/chromium/base/metrics/RecordHistogramTest.java
@@ -80,6 +80,47 @@ public class RecordHistogramTest extends InstrumentationTestCase {
     }
 
     /**
+     * Tests recording of count histograms.
+     */
+    @SmallTest
+    public void testRecordCountHistogram() {
+        String histogram = "HelloWorld.CountMetric";
+        HistogramDelta zeroCount = new HistogramDelta(histogram, 0);
+        HistogramDelta oneCount = new HistogramDelta(histogram, 1);
+        HistogramDelta twoCount = new HistogramDelta(histogram, 2);
+        HistogramDelta eightThousandCount = new HistogramDelta(histogram, 8000);
+
+        assertEquals(0, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(0, twoCount.getDelta());
+        assertEquals(0, eightThousandCount.getDelta());
+
+        RecordHistogram.recordCountHistogram(histogram, 0);
+        assertEquals(1, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(0, twoCount.getDelta());
+        assertEquals(0, eightThousandCount.getDelta());
+
+        RecordHistogram.recordCountHistogram(histogram, 0);
+        assertEquals(2, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(0, twoCount.getDelta());
+        assertEquals(0, eightThousandCount.getDelta());
+
+        RecordHistogram.recordCountHistogram(histogram, 2);
+        assertEquals(2, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(1, twoCount.getDelta());
+        assertEquals(0, eightThousandCount.getDelta());
+
+        RecordHistogram.recordCountHistogram(histogram, 8000);
+        assertEquals(2, zeroCount.getDelta());
+        assertEquals(0, oneCount.getDelta());
+        assertEquals(1, twoCount.getDelta());
+        assertEquals(1, eightThousandCount.getDelta());
+    }
+
+    /**
      * Tests recording of custom times histograms.
      */
     @SmallTest
diff --git a/base/android/record_histogram.cc b/base/android/record_histogram.cc
index 0df0487..8b7f7bd 100644
--- a/base/android/record_histogram.cc
+++ b/base/android/record_histogram.cc
@@ -60,6 +60,31 @@ class HistogramCache {
     return InsertLocked(j_histogram_key, histogram);
   }
 
+  HistogramBase* CountHistogram(JNIEnv* env,
+                                jstring j_histogram_name,
+                                jint j_histogram_key) {
+    // These values are based on the hard-coded constants in the
+    // UMA_HISTOGRAM_COUNTS macro from base/metrics/histogram_macros.h.
+    const int histogram_min = 1;
+    const int histogram_max = 1000000;
+    const int histogram_num_buckets = 50;
+
+    DCHECK(j_histogram_name);
+    DCHECK(j_histogram_key);
+    HistogramBase* histogram = FindLocked(j_histogram_key);
+    if (histogram) {
+      DCHECK(histogram->HasConstructionArguments(histogram_min, histogram_max,
+                                                 histogram_num_buckets));
+      return histogram;
+    }
+
+    std::string histogram_name = ConvertJavaStringToUTF8(env, j_histogram_name);
+    histogram = Histogram::FactoryGet(histogram_name, histogram_min,
+                                      histogram_max, histogram_num_buckets,
+                                      HistogramBase::kUmaTargetedHistogramFlag);
+    return InsertLocked(j_histogram_key, histogram);
+  }
+
   HistogramBase* CustomTimesHistogram(JNIEnv* env,
                                       jstring j_histogram_name,
                                       jint j_histogram_key,
@@ -133,6 +158,18 @@ void RecordEnumeratedHistogram(JNIEnv* env,
       ->Add(sample);
 }
 
+void RecordCountHistogram(JNIEnv* env,
+                          jclass clazz,
+                          jstring j_histogram_name,
+                          jint j_histogram_key,
+                          jint j_sample) {
+  int sample = static_cast<int>(j_sample);
+
+  g_histograms.Get()
+      .CountHistogram(env, j_histogram_name, j_histogram_key)
+      ->Add(sample);
+}
+
 void RecordCustomTimesHistogramMilliseconds(JNIEnv* env,
                                             jclass clazz,
                                             jstring j_histogram_name,