Refactoring the way begin frame sources inside scheduler work.

cc/BUILD.gn

 # Copyright 2014 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.
 
 component("cc") {
   sources = [
     "animation/animation.cc",
     "animation/animation.h",
     "animation/animation_curve.cc",
     "animation/animation_curve.h",
@@ skipping 413 matching lines @@
     "resources/ui_resource_bitmap.cc",
     "resources/ui_resource_bitmap.h",
     "resources/ui_resource_client.h",
     "resources/ui_resource_request.cc",
     "resources/ui_resource_request.h",
     "resources/video_resource_updater.cc",
     "resources/video_resource_updater.h",
     "scheduler/delay_based_time_source.cc",
     "scheduler/delay_based_time_source.h",
     "scheduler/draw_result.h",
+    "scheduler/frame_source.cc",
+    "scheduler/frame_source.h",
     "scheduler/scheduler.cc",
     "scheduler/scheduler.h",
     "scheduler/scheduler_settings.cc",
     "scheduler/scheduler_settings.h",
     "scheduler/scheduler_state_machine.cc",
     "scheduler/scheduler_state_machine.h",
     "trees/blocking_task_runner.cc",
     "trees/blocking_task_runner.h",
     "trees/damage_tracker.cc",
     "trees/damage_tracker.h",
@@ skipping 282 matching lines @@
     "resources/resource_provider_unittest.cc",
     "resources/resource_update_controller_unittest.cc",
     "resources/scoped_resource_unittest.cc",
     "resources/task_graph_runner_unittest.cc",
     "resources/texture_mailbox_deleter_unittest.cc",
     "resources/texture_uploader_unittest.cc",
     "resources/tile_manager_unittest.cc",
     "resources/tile_priority_unittest.cc",
     "resources/video_resource_updater_unittest.cc",
     "scheduler/delay_based_time_source_unittest.cc",
+    "scheduler/frame_source_unittest.cc",
     "scheduler/scheduler_state_machine_unittest.cc",
     "scheduler/scheduler_unittest.cc",
     "test/layer_tree_json_parser_unittest.cc",
     "test/test_web_graphics_context_3d_unittest.cc",
     "trees/blocking_task_runner_unittest.cc",
     "trees/damage_tracker_unittest.cc",
     "trees/layer_sorter_unittest.cc",
     "trees/layer_tree_host_common_unittest.cc",
     "trees/layer_tree_host_impl_unittest.cc",
     "trees/layer_tree_host_pixeltest_blending.cc",
@@ skipping 72 matching lines @@
     "//gpu/command_buffer/common:gles2_utils",
     "//media",
     "//skia",
     "//testing/gmock",
     "//testing/gtest",
     "//testing/perf",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
 }