cc: Add command line for frame production throttle

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 206 matching lines @@
 
 void RenderWidgetCompositor::Initialize() {
   base::CommandLine* cmd = base::CommandLine::ForCurrentProcess();
 
   cc::LayerTreeSettings settings;
 
   // For web contents, layer transforms should scale up the contents of layers
   // to keep content always crisp when possible.
   settings.layer_transforms_should_scale_layer_contents = true;
 
-  settings.renderer_settings.disable_gpu_vsync =
-      cmd->HasSwitch(switches::kDisableGpuVsync);
+  settings.renderer_settings.disable_display_vsync =

[danakj, 2015/07/01 19:47:23]

wow is this confusing.

we have 2 flags that you can set either one to do one thing.
we have 2 overlapping/different flags that must both be off to do another thing.

brian, is this really the best we can do?

[brianderson, 2015/07/01 20:51:57]

From a code readability perspective, I agree it's pretty bad. But from a user's
perspective I think it makes sense.

Most users just want to use --disable-gpu-vsync to disable both (like they can
at ToT today). Very few users will care about disabling one or the other
individually.

Would it help code readability if "throttle_frame_production" became
"disable_begin_frame_interval" so we don't have the double negation?

+      (cmd->HasSwitch(switches::kDisableGpuVsync) ||
+       cmd->HasSwitch(switches::kDisableDisplayVsync));
+  settings.throttle_frame_production =
+      !(cmd->HasSwitch(switches::kDisableGpuVsync) ||
+        cmd->HasSwitch(cc::switches::kDisableBeginFrameInterval));
+
   settings.main_frame_before_activation_enabled =
       cmd->HasSwitch(cc::switches::kEnableMainFrameBeforeActivation) &&
       !cmd->HasSwitch(cc::switches::kDisableMainFrameBeforeActivation);
   settings.report_overscroll_only_for_scrollable_axes =
       !compositor_deps_->IsElasticOverscrollEnabled();
   settings.accelerated_animation_enabled =
       !cmd->HasSwitch(cc::switches::kDisableThreadedAnimation);
   settings.use_display_lists = cmd->HasSwitch(switches::kEnableSlimmingPaint);
   if (cmd->HasSwitch(switches::kEnableCompositorAnimationTimelines)) {
     settings.use_compositor_animation_timelines = true;
@@ skipping 762 matching lines @@
     return;
   provider->ContextGL()->RateLimitOffscreenContextCHROMIUM();
 }
 
 void RenderWidgetCompositor::SetSurfaceIdNamespace(
     uint32_t surface_id_namespace) {
   layer_tree_host_->set_surface_id_namespace(surface_id_namespace);
 }
 
 }  // namespace content