Refactor renderer LayerTreeSettings generating code to common.

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index 82e555b9d7e8d5d0914c39327709519759033985..c1ef5e0a9876e2e84eb6f54be312ff2b1e7cc7b4 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -41,6 +41,7 @@
 #include "cc/trees/latency_info_swap_promise_monitor.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/remote_proto_channel.h"
+#include "content/common/compositor_util.h"
 #include "content/common/content_switches_internal.h"
 #include "content/common/gpu/client/context_provider_command_buffer.h"
 #include "content/public/common/content_client.h"
@@ -344,14 +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;
-  }
+  // Build LayerTreeSettings from command line args.
+  CompositorUtil::GenerateLayerTreeSettings(settings, cmd);

[Khushal, 2016/08/29 20:21:14]

Do you want to just call it SetTopControlsSettings and move the part below as
well, they belong together. Its nice that we decompose this massive function
into these units now that we're moving it.

Later on you can put all these small functions within the compositor_util.cc
file itself and expose just one GenerateRendererLayerTreeSettings that will call
all of these.

[xingliu, 2016/08/29 20:44:33]

Done.

 
   if (cmd.HasSwitch(cc::switches::kTopControlsHideThreshold)) {
     std::string top_threshold_str =