Add support for passing errors through PopulateArrayFromList.

tools/json_schema_compiler/test/error_generation_unittest.cc

Index: tools/json_schema_compiler/test/error_generation_unittest.cc
diff --git a/tools/json_schema_compiler/test/error_generation_unittest.cc b/tools/json_schema_compiler/test/error_generation_unittest.cc
index 42f95760a64825d13a79b4477ca6191bda622335..904b6c9739ab7bd852fc52fb35970a0e0cd89205 100644
--- a/tools/json_schema_compiler/test/error_generation_unittest.cc
+++ b/tools/json_schema_compiler/test/error_generation_unittest.cc
@@ -170,7 +170,8 @@ TEST(JsonSchemaCompilerErrorTest, UnableToPopulateArray) {
     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)));
   }
 }
@@ -294,7 +295,8 @@ TEST(JsonSchemaCompilerErrorTest, OptionalUnableToPopulateArray) {
     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());
   }