[Cleanup] Add missing #include. Remove useless ones. IWYU part 2.

This is a follow-up to
https://webrtc-review.googlesource.com/c/src/+/106280.
This time the whole code base is covered.
Some files may have not been fixed though, whenever the IWYU tool
was breaking the build.

Bug: webrtc:8311
Change-Id: I2c31f552a87e887d33931d46e87b6208b1e483ef
Reviewed-on: https://webrtc-review.googlesource.com/c/111965
Commit-Queue: Yves Gerey <yvesg@google.com>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25830}
diff --git a/video/cpu_scaling_tests.cc b/video/cpu_scaling_tests.cc
index 608f05e..c4d1b1e 100644
--- a/video/cpu_scaling_tests.cc
+++ b/video/cpu_scaling_tests.cc
@@ -8,9 +8,22 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include <limits>
+#include <vector>
+
+#include "api/rtpparameters.h"
+#include "api/video/video_frame.h"
+#include "api/video/video_sink_interface.h"
+#include "api/video/video_source_interface.h"
+#include "api/video_codecs/video_encoder_config.h"
+#include "call/video_receive_stream.h"
+#include "call/video_send_stream.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/event.h"
 #include "test/call_test.h"
 #include "test/field_trial.h"
 #include "test/frame_generator_capturer.h"
+#include "test/gtest.h"
 
 namespace webrtc {
 namespace {