Start to refactor renderer LayerTreeSettings generating code to common.

The goal is to let Blimp reuse this logic on browser process, since
Blimp client doesn't have renderer process.

BUG=577985

Review-Url: https://codereview.chromium.org/2285083004
Cr-Commit-Position: refs/heads/master@{#415366}

content/common/layer_tree_settings_factory.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/layer_tree_settings_factory.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "cc/base/switches.h"
+
+namespace content {
+
+// static
+void LayerTreeSettingsFactory::SetTopControlsSettings(
+    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;
+  }
+
+  if (cmd.HasSwitch(cc::switches::kTopControlsHideThreshold)) {
+    std::string top_threshold_str =
+        cmd.GetSwitchValueASCII(cc::switches::kTopControlsHideThreshold);
+    double hide_threshold;
+    if (base::StringToDouble(top_threshold_str, &hide_threshold) &&
+        hide_threshold >= 0.f && hide_threshold <= 1.f)
+      settings.top_controls_hide_threshold = hide_threshold;
+  }
+}
+
+}  // namespace content

content/common/layer_tree_settings_factory.h

+// 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.
+
+#ifndef CONTENT_COMMON_LAYER_TREE_SETTINGS_FACTORY_H_
+#define CONTENT_COMMON_LAYER_TREE_SETTINGS_FACTORY_H_
+
+#include "base/command_line.h"
+#include "base/macros.h"
+#include "cc/trees/layer_tree_settings.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+// LayerTreeSettingsFactory holds utilities functions to generate
+// LayerTreeSettings.
+class CONTENT_EXPORT LayerTreeSettingsFactory {
+  // TODO(xingliu): Refactor LayerTreeSettings generation logic.
+  // crbug.com/577985
+ public:
+  static void SetTopControlsSettings(cc::LayerTreeSettings& settings,
+                                     const base::CommandLine& command_line);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_LAYER_TREE_SETTINGS_FACTORY_H_

content/content_common.gypi

@@ -398,6 +398,8 @@
       'common/input_messages.h',
       'common/inter_process_time_ticks_converter.cc',
       'common/inter_process_time_ticks_converter.h',
+      'common/layer_tree_settings_factory.cc',
+      'common/layer_tree_settings_factory.h',
       'common/mac/attributed_string_coder.h',
       'common/mac/attributed_string_coder.mm',
       'common/mac/font_descriptor.h',

content/renderer/gpu/render_widget_compositor.cc

@@ -43,6 +43,7 @@
 #include "cc/trees/remote_proto_channel.h"
 #include "content/common/content_switches_internal.h"
 #include "content/common/gpu/client/context_provider_command_buffer.h"
+#include "content/common/layer_tree_settings_factory.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
 #include "content/renderer/gpu/render_widget_compositor_delegate.h"
@@ -344,23 +345,8 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
   settings.image_decode_tasks_enabled =
       compositor_deps->AreImageDecodeTasksEnabled();
 
-  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;
-  }
-
-  if (cmd.HasSwitch(cc::switches::kTopControlsHideThreshold)) {
-    std::string top_threshold_str =
-        cmd.GetSwitchValueASCII(cc::switches::kTopControlsHideThreshold);
-    double hide_threshold;
-    if (base::StringToDouble(top_threshold_str, &hide_threshold) &&
-        hide_threshold >= 0.f && hide_threshold <= 1.f)
-      settings.top_controls_hide_threshold = hide_threshold;
-  }
+  // Build LayerTreeSettings from command line args.
+  LayerTreeSettingsFactory::SetTopControlsSettings(settings, cmd);
 
   settings.use_layer_lists = cmd.HasSwitch(cc::switches::kEnableLayerLists);