[CodeHealth] Remove uses of ListValue::begin()/end() in /content/brow…

…ser/devtools/protocol.

This CL removes calls to these deprecated member functions. It also
converts to the newer "for" loop syntax when possible, along with
other minor cleanup.

This CL was uploaded by git cl split.

R=yangguo@chromium.org

Bug: 1187107
Change-Id: I07c37c1ac3f58c8956294c592f01e8e1d4996793
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2877401
Auto-Submit: David Bertoni <dbertoni@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#880061}

content/browser/devtools/protocol/devtools_protocol_browsertest.cc

@@ -102,7 +102,7 @@ bool GetCertificateFromNotificationParams(base::DictionaryValue* params,
   if (!params->GetList("explanations", &explanations)) {
     return false;
   }
-  for (const auto& explanation : *explanations) {
+  for (const auto& explanation : explanations->GetList()) {
     const base::DictionaryValue* explanation_dict;
     if (explanation.GetAsDictionary(&explanation_dict) &&
         explanation_dict->GetList("certificate", certificate) &&
@@ -2221,7 +2221,7 @@ IN_PROC_BROWSER_TEST_F(DevToolsProtocolTest, CertificateExplanations) {
   const base::ListValue* certificate;
   ASSERT_TRUE(GetCertificateFromNotificationParams(params.get(), &certificate));
   std::vector<std::string> der_certs;
-  for (const auto& cert : *certificate) {
+  for (const auto& cert : certificate->GetList()) {
     std::string decoded;
     ASSERT_TRUE(base::Base64Decode(cert.GetString(), &decoded));
     der_certs.push_back(decoded);

content/browser/devtools/protocol/tracing_handler.cc

@@ -102,7 +102,7 @@ std::unique_ptr<base::Value> ConvertDictKeyStyle(const base::Value& value) {
   const base::ListValue* list = nullptr;
   if (value.GetAsList(&list)) {
     std::unique_ptr<base::ListValue> out_list(new base::ListValue());
-    for (const auto& key : *list)
+    for (const auto& key : list->GetList())
       out_list->Append(ConvertDictKeyStyle(key));
     return std::move(out_list);
   }