Return a NULL histogram pointer on construction error

ppapi/tests/test_uma.cc

 // Copyright (c) 2011 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.
 
 #include "ppapi/tests/test_uma.h"
 
 #include "ppapi/cpp/instance.h"
 #include "ppapi/cpp/module.h"
 #include "ppapi/tests/testing_instance.h"
 
@@ skipping 12 matching lines @@
 }
 
 std::string TestUMA::TestCount() {
   pp::Var name_var = pp::Var("Test.CountHistogram");
   PP_Var name = name_var.pp_var();
   PP_Instance instance = instance_->pp_instance();
   uma_interface_->HistogramCustomCounts(instance, name, 10, 1, 100, 50);
   uma_interface_->HistogramCustomCounts(instance, name, 30, 1, 100, 50);
   uma_interface_->HistogramCustomCounts(instance, name, 20, 1, 100, 50);
   uma_interface_->HistogramCustomCounts(instance, name, 40, 1, 100, 50);
+  // Test that passing in different construction arguments for the same
+  // histogram name does not crash.
+  uma_interface_->HistogramCustomCounts(instance, name, 40, 1, 100, 100);
+  uma_interface_->HistogramCustomCounts(instance, name, 40, 1, 90, 50);
+  uma_interface_->HistogramCustomCounts(instance, name, 40, 10, 100, 50);
   PASS();
 }
 
 std::string TestUMA::TestTime() {
   pp::Var name_var = pp::Var("Test.TimeHistogram");
   PP_Var name = name_var.pp_var();
   PP_Instance instance = instance_->pp_instance();
   uma_interface_->HistogramCustomTimes(instance, name, 100, 1, 10000, 50);
   uma_interface_->HistogramCustomTimes(instance, name, 1000, 1, 10000, 50);
   uma_interface_->HistogramCustomTimes(instance, name, 5000, 1, 10000, 50);
   uma_interface_->HistogramCustomTimes(instance, name, 10, 1, 10000, 50);
+  // Test that passing in different construction arguments for the same
+  // histogram name does not crash.
+  uma_interface_->HistogramCustomTimes(instance, name, 10, 1, 10000, 100);
+  uma_interface_->HistogramCustomTimes(instance, name, 10, 1, 9000, 50);
+  uma_interface_->HistogramCustomTimes(instance, name, 10, 100, 10000, 50);
   PASS();
 }
 
 std::string TestUMA::TestEnum() {
   pp::Var name_var = pp::Var("Test.EnumHistogram");
   PP_Var name = name_var.pp_var();
   PP_Instance instance = instance_->pp_instance();
   uma_interface_->HistogramEnumeration(instance, name, 0, 5);
   uma_interface_->HistogramEnumeration(instance, name, 3, 5);
   uma_interface_->HistogramEnumeration(instance, name, 3, 5);
   uma_interface_->HistogramEnumeration(instance, name, 1, 5);
   uma_interface_->HistogramEnumeration(instance, name, 2, 5);
+  // Test that passing in different construction arguments for the same
+  // histogram name does not crash.
+  uma_interface_->HistogramEnumeration(instance, name, 2, 6);
   PASS();
 }