[Extensions Binding] Update ArgumentSpec to support dictionary enums

The enum definitions in our schemas can either be in the form of a list
value with string entries (e.g. "enum": ["foo", "bar", "baz"]) or in the
form of a dictionary with a name entry (e.g. "enum": [{"name": "foo"}]).

Adjust ArgumentSpec to account for the latter, and add tests.

BUG=653596

Review-Url: https://chromiumcodereview.appspot.com/2439263003
Cr-Commit-Position: refs/heads/master@{#426999}

extensions/renderer/argument_spec.cc

@@ -93,7 +93,13 @@ void ArgumentSpec::InitializeType(const base::DictionaryValue* dict) {
       CHECK_GT(size, 0u);
       for (size_t i = 0; i < size; ++i) {
         std::string enum_value;
-        CHECK(enums->GetString(i, &enum_value));
+        // Enum entries come in two versions: a list of possible strings, and
+        // a dictionary with a field 'name'.
+        if (!enums->GetString(i, &enum_value)) {
+          const base::DictionaryValue* enum_value_dictionary = nullptr;
+          CHECK(enums->GetDictionary(i, &enum_value_dictionary));
+          CHECK(enum_value_dictionary->GetString("name", &enum_value));
+        }
         enum_values_.insert(std::move(enum_value));
       }
     }

extensions/renderer/argument_spec_unittest.cc

@@ -129,6 +129,18 @@ TEST_F(ArgumentSpecUnitTest, Test) {
     ExpectFailure(spec, "''");
   }
 
+  {
+    ArgumentSpec spec(*ValueFromString(
+        "{'type': 'string', 'enum': [{'name': 'foo'}, {'name': 'bar'}]}"));
+    ExpectSuccess(spec, "'foo'", "'foo'");
+    ExpectSuccess(spec, "'bar'", "'bar'");
+    ExpectFailure(spec, "['foo']");
+    ExpectFailure(spec, "'fo'");
+    ExpectFailure(spec, "'foobar'");
+    ExpectFailure(spec, "'baz'");
+    ExpectFailure(spec, "''");
+  }
+
   {
     ArgumentSpec spec(*ValueFromString("{'type': 'boolean'}"));
     ExpectSuccess(spec, "true", "true");