Work around exceptions when the 'high' value for a histogram is not present. This happens when the …

tools/telemetry/telemetry/value/histogram_util_unittest.py

Index: tools/telemetry/telemetry/value/histogram_util_unittest.py
diff --git a/tools/telemetry/telemetry/value/histogram_util_unittest.py b/tools/telemetry/telemetry/value/histogram_util_unittest.py
index a91d0f9f21bf4ce46adf5dc9ef04a33ddbd09ed3..d20cacafb510334902e2abc3bc307148827989d7 100644
--- a/tools/telemetry/telemetry/value/histogram_util_unittest.py
+++ b/tools/telemetry/telemetry/value/histogram_util_unittest.py
@@ -50,3 +50,31 @@ class TestHistogram(unittest.TestCase):
     self.assertEquals(5, new_buckets[1])
     self.assertEquals(12, new_buckets[2])
     self.assertEquals(21, new_buckets[3])
+
+
+  def testGetHistogramBucketsFromRawValue_Max(self):
+    raw_value = {'buckets': [
+      {'count': 4, 'low': 10, 'high': 15,},
+      {'count': 6, 'low': 16, 'high': 18,},
+      {'count': 8, 'low': 19},
+    ]}
+    buckets = histogram_util.GetHistogramBucketsFromRawValue(raw_value)
+    self.assertEquals([
+      {'count': 4, 'low': 10, 'high': 15,},
+      {'count': 6, 'low': 16, 'high': 18,},
+      {'count': 8, 'low': 19, 'high': 19},],
+      buckets)
+
+
+  def testGetHistogramBucketsFromJson(self):
+    json_value = json.dumps({'buckets': [
+      {'count': 4, 'low': 10, 'high': 15,},
+      {'count': 6, 'low': 16, 'high': 18,},
+      {'count': 8, 'low': 19, 'high': 25},
+    ]})
+    buckets = histogram_util.GetHistogramBucketsFromJson(json_value)
+    self.assertEquals([
+      {'count': 4, 'low': 10, 'high': 15,},
+      {'count': 6, 'low': 16, 'high': 18,},
+      {'count': 8, 'low': 19, 'high': 25},],
+      buckets)