toggle FPS counter in compositor

ui/compositor/compositor.cc

 // Copyright (c) 2012 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 "ui/compositor/compositor.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/threading/thread_restrictions.h"
@@ skipping 129 matching lines @@
       swap_posted_(false),
       device_scale_factor_(0.0f),
       last_started_frame_(0),
       last_ended_frame_(0),
       disable_schedule_composite_(false) {
   WebKit::WebCompositorSupport* compositor_support =
       WebKit::Platform::current()->compositorSupport();
   root_web_layer_.reset(compositor_support->createLayer());
   WebKit::WebLayerTreeView::Settings settings;
   CommandLine* command_line = CommandLine::ForCurrentProcess();
-  settings.showFPSCounter =

[enne (OOO), 2012/10/29 17:58:57]

Won't this break the --ui-show-fps-counter flag, since there's no corresponding
calls to showFPSCounter? I think you might be missing a
host_->setShowFPSCounter(...) call here to counteract that.

[egraether, 2012/10/30 00:03:57]

I did not realize that this was a different flag when I removed that. Anyhow, I
started testing what it did and if your suggestion works, but I couldn't figure
out what this does so far.
When is a Compositor instantiated? What is the --ui-show-fps-counter flag for?

[enne (OOO), 2012/10/30 16:09:45]

It's for Aura builds, which has a separate compositor in the browser process. 
This allows a top-level FPS counter for the desktop rather than on each tab.

[egraether, 2012/10/30 16:41:34]

And how is the fontAtlas loaded in that case?

[egraether, 2012/10/30 20:14:04]

It isn't and that caused some problems.
I removed the change here and re-added showFPSCounter to the
WebLayerTreeView::Settings, so --ui-show-fps-counter works again. I did not use
host_->setShowFPSCounter() instead, because that causes a dependency on the
associated WebKit patch which defines the method setShowFPSCounter.

-      command_line->HasSwitch(switches::kUIShowFPSCounter);
   settings.showPlatformLayerTree =
       command_line->HasSwitch(switches::kUIShowLayerTree);
   settings.refreshRate =
       test_compositor_enabled ? kTestRefreshRate : kDefaultRefreshRate;
 
   root_web_layer_->setAnchorPoint(WebKit::WebFloatPoint(0.f, 0.f));
   host_.reset(compositor_support->createLayerTreeView(this, *root_web_layer_,
                                                       settings));
   host_->setSurfaceReady();
 }
@@ skipping 273 matching lines @@
 
 COMPOSITOR_EXPORT void DisableTestCompositor() {
   test_compositor_enabled = false;
 }
 
 COMPOSITOR_EXPORT bool IsTestCompositorEnabled() {
   return test_compositor_enabled;
 }
 
 }  // namespace ui