Refactor renderer LayerTreeSettings generating code to common.

content/common/compositor_util.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 "content/common/compositor_util.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "cc/base/switches.h"
+
+namespace content {
+
+// static
+void CompositorUtil::GenerateLayerTreeSettings(cc::LayerTreeSettings& settings,
+                                               const base::CommandLine& cmd) {
+  if (cmd.HasSwitch(cc::switches::kTopControlsShowThreshold)) {
+    std::string top_threshold_str =
+        cmd.GetSwitchValueASCII(cc::switches::kTopControlsShowThreshold);
+    double show_threshold;
+    if (base::StringToDouble(top_threshold_str, &show_threshold) &&
+        show_threshold >= 0.f && show_threshold <= 1.f)
+      settings.top_controls_show_threshold = show_threshold;
+  }
+}
+
+}  // namespace content