[Android WebView] Add functionality to enable features and enable the spellcheck feature.

android_webview/browser/command_line_helper.cc

+// Copyright 2016 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 "android_webview/browser/command_line_helper.h"
+
+#include <algorithm>
+#include <vector>
+
+#include "base/command_line.h"
+#include "base/feature_list.h"
+#include "base/strings/string_util.h"
+#include "content/public/common/content_switches.h"
+
+using std::string;
+using std::vector;
+
+namespace {
+
+bool contains(const vector<string>& features, const string& feature_name) {

[Tobias Sargeant, 2016/10/05 13:56:15]

This is base::ContainsValue in base/stl_util.h

[timvolodine, 2016/10/06 11:58:42]

yes thanks, I thought there should be something in base for this.. Done

+  return std::find(features.begin(), features.end(), feature_name) !=
+         features.end();
+}
+
+}  // namespace
+
+// static
+void CommandLineHelper::AddEnabledFeature(base::CommandLine& command_line,
+                                          const string& feature_name) {
+  string enabled_features_list =
+      command_line.GetSwitchValueASCII(switches::kEnableFeatures);
+  string disabled_features_list =
+      command_line.GetSwitchValueASCII(switches::kDisableFeatures);
+
+  if (enabled_features_list.empty() && disabled_features_list.empty()) {
+    command_line.AppendSwitchASCII(switches::kEnableFeatures, feature_name);
+    return;
+  }
+
+  vector<string> enabled_features =
+      base::FeatureList::SplitFeatureListString(enabled_features_list);
+  vector<string> disabled_features =
+      base::FeatureList::SplitFeatureListString(disabled_features_list);
+
+  if (!contains(enabled_features, feature_name) &&
+      !contains(disabled_features, feature_name)) {
+    enabled_features.push_back(feature_name);
+    command_line.AppendSwitchASCII(switches::kEnableFeatures,
+                                   base::JoinString(enabled_features, ","));
+  }
+}