Remove external begin frame source parameter and settings

cc/trees/layer_tree_settings.cc

 // Copyright 2011 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 "cc/trees/layer_tree_settings.h"
 
 #include "cc/proto/gfx_conversions.h"
 #include "third_party/khronos/GLES2/gl2.h"
 
 namespace cc {
 
 LayerTreeSettings::LayerTreeSettings()
     : default_tile_size(gfx::Size(256, 256)),
       max_untiled_layer_size(gfx::Size(512, 512)),
       minimum_occlusion_tracking_size(gfx::Size(160, 160)),
       gpu_memory_policy(64 * 1024 * 1024,
                         gpu::MemoryAllocation::CUTOFF_ALLOW_EVERYTHING,
                         ManagedMemoryPolicy::kDefaultNumResourcesLimit),
       software_memory_policy(128 * 1024 * 1024,
                              gpu::MemoryAllocation::CUTOFF_ALLOW_NICE_TO_HAVE,
                              ManagedMemoryPolicy::kDefaultNumResourcesLimit) {}
 
 LayerTreeSettings::LayerTreeSettings(const LayerTreeSettings& other) = default;
 LayerTreeSettings::~LayerTreeSettings() = default;
 
 bool LayerTreeSettings::operator==(const LayerTreeSettings& other) const {
   return renderer_settings == other.renderer_settings &&
          single_thread_proxy_scheduler == other.single_thread_proxy_scheduler &&
-         use_external_begin_frame_source ==
-             other.use_external_begin_frame_source &&
          main_frame_before_activation_enabled ==
              other.main_frame_before_activation_enabled &&
          using_synchronous_renderer_compositor ==
              other.using_synchronous_renderer_compositor &&
          enable_latency_recovery == other.enable_latency_recovery &&
          can_use_lcd_text == other.can_use_lcd_text &&
          use_distance_field_text == other.use_distance_field_text &&
          gpu_rasterization_enabled == other.gpu_rasterization_enabled &&
          gpu_rasterization_forced == other.gpu_rasterization_forced &&
          async_worker_context_enabled == other.async_worker_context_enabled &&
@@ skipping 58 matching lines @@
       using_synchronous_renderer_compositor;
   scheduler_settings.enable_latency_recovery = enable_latency_recovery;
   scheduler_settings.background_frame_interval =
       base::TimeDelta::FromSecondsD(1.0 / background_animation_rate);
   scheduler_settings.abort_commit_before_compositor_frame_sink_creation =
       abort_commit_before_compositor_frame_sink_creation;
   return scheduler_settings;
 }
 
 }  // namespace cc