Add support for passing errors through PopulateArrayFromList.

tools/json_schema_compiler/test/error_generation_unittest.cc

 // Copyright 2013 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 "tools/json_schema_compiler/test/error_generation.h"
 
 #include "base/json/json_writer.h"
 #include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/json_schema_compiler/test/test_util.h"
@@ skipping 152 matching lines @@
   {
     scoped_ptr<base::ListValue> params_value = List(
         new FundamentalValue(5));
     EXPECT_TRUE(EqualsUtf16("",
         GetPopulateError<ChoiceType::Integers>(*params_value)));
   }
   {
     scoped_ptr<base::ListValue> params_value = List(
         new FundamentalValue(5),
         new FundamentalValue(false));
-    EXPECT_TRUE(EqualsUtf16("unable to populate array 'integers'",
+    EXPECT_TRUE(EqualsUtf16(
+        "expected integer, got boolean; unable to populate array 'integers'",
         GetPopulateError<ChoiceType::Integers>(*params_value)));
   }
 }
 
 TEST(JsonSchemaCompilerErrorTest, BinaryTypeExpected) {
   {
     scoped_ptr<base::DictionaryValue> value = Dictionary(
         "data", new base::BinaryValue());
     EXPECT_TRUE(EqualsUtf16("", GetPopulateError<BinaryData>(*value)));
   }
@@ skipping 103 matching lines @@
         GetPopulateError<OptionalChoiceType::Integers>(*params_value)));
   }
   {
     scoped_ptr<base::ListValue> params_value = List(
         new FundamentalValue(5),
         new FundamentalValue(false));
     OptionalChoiceType::Integers out;
     base::string16 error;
     EXPECT_TRUE(OptionalChoiceType::Integers::Populate(*params_value, &out,
         &error));
-    EXPECT_TRUE(EqualsUtf16("unable to populate array 'integers'",
+    EXPECT_TRUE(EqualsUtf16(
+        "expected integer, got boolean; unable to populate array 'integers'",
         error));
     EXPECT_EQ(NULL, out.as_integer.get());
   }
 }
 
 TEST(JsonSchemaCompilerErrorTest, MultiplePopulationErrors) {
   {
 
     scoped_ptr<base::DictionaryValue> value = Dictionary(
         "TheArray", new FundamentalValue(5));
@@ skipping 19 matching lines @@
     EXPECT_TRUE(EqualsUtf16("", GetPopulateError<TestType>(*value)));
   }
   {
     scoped_ptr<base::DictionaryValue> value = Dictionary(
         "string", new base::StringValue("yes"),
         "ohno", new base::StringValue("many values"));
     EXPECT_TRUE(EqualsUtf16("found unexpected key 'ohno'",
         GetPopulateError<TestType>(*value)));
   }
 }