cc: Separate raster and decode prepaint regions.

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 <GLES2/gl2.h>
 #include <stddef.h>
 #include <limits>
 
@@ skipping 92 matching lines @@
       wait_for_beginframe_interval(true),
       abort_commit_before_output_surface_creation(true),
       use_mouse_wheel_gestures(false),
       use_layer_lists(false),
       max_staging_buffer_usage_in_bytes(32 * 1024 * 1024),
       memory_policy_(64 * 1024 * 1024,
                      gpu::MemoryAllocation::CUTOFF_ALLOW_EVERYTHING,
                      ManagedMemoryPolicy::kDefaultNumResourcesLimit),
       gpu_decoded_image_budget_bytes(96 * 1024 * 1024),
       software_decoded_image_budget_bytes(128 * 1024 * 1024),
+      max_preraster_distance_in_screen_pixels(1000),

[ericrk, 2016/05/24 23:42:34]

I'm curious if we should use an even lower limit for GPU? With the skewport
target time set to 0.2s for GPU, you'd have to scroll at a rate of 5000 pixels
per second to hit this - additionally, GPU should be able to raster more quickly
than SW, especially if no image decodes are necessary.

[vmpstr, 2016/06/07 20:43:55]

That's entirely possible. Eventually I'd like this to be close to 0, however I'm
trying to deliberately be a bit conservative so that we don't break things if
our assumptions about imageless raster speed are wrong. Do you think this is a
good value to start with?

       use_cached_picture_raster(true) {}
 
 LayerTreeSettings::LayerTreeSettings(const LayerTreeSettings& other) = default;
 
 LayerTreeSettings::~LayerTreeSettings() {}
 
 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 ==
@@ skipping 195 matching lines @@
       using_synchronous_renderer_compositor;
   scheduler_settings.throttle_frame_production = wait_for_beginframe_interval;
   scheduler_settings.background_frame_interval =
       base::TimeDelta::FromSecondsD(1.0 / background_animation_rate);
   scheduler_settings.abort_commit_before_output_surface_creation =
       abort_commit_before_output_surface_creation;
   return scheduler_settings;
 }
 
 }  // namespace cc