Fix VideoStreamEncoder QP tests to not use SetHasInternalSource

The has_internal_source feature is deprecated, and unrelated to the
tests of QP parsing.

Bug: webtc:12875
Change-Id: Ib43063ebf49e6e0bd7a5328a04ba2816f3a7ecb2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/222400
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34280}

video/video_stream_encoder_unittest.cc

diff --git a/video/video_stream_encoder_unittest.cc b/video/video_stream_encoder_unittest.cc
index d359282..cbfd93e 100644
--- a/video/video_stream_encoder_unittest.cc
+++ b/video/video_stream_encoder_unittest.cc
@@ -8095,10 +8095,13 @@
 }
 
 TEST_F(VideoStreamEncoderTest, QpPresent_QpKept) {
-  // Enable encoder source to force encoder reconfig.
-  encoder_factory_.SetHasInternalSource(true);
   ResetEncoder("VP8", 1, 1, 1, false);
 
+  // Force encoder reconfig.
+  video_source_.IncomingCapturedFrame(
+      CreateFrame(1, codec_width_, codec_height_));
+  video_stream_encoder_->WaitUntilTaskQueueIsIdle();
+
   // Set QP on encoded frame and pass the frame to encode complete callback.
   // Since QP is present QP parsing won't be triggered and the original value
   // should be kept.
@@ -8115,10 +8118,13 @@
 }
 
 TEST_F(VideoStreamEncoderTest, QpAbsent_QpParsed) {
-  // Enable encoder source to force encoder reconfig.
-  encoder_factory_.SetHasInternalSource(true);
   ResetEncoder("VP8", 1, 1, 1, false);
 
+  // Force encoder reconfig.
+  video_source_.IncomingCapturedFrame(
+      CreateFrame(1, codec_width_, codec_height_));
+  video_stream_encoder_->WaitUntilTaskQueueIsIdle();
+
   // Pass an encoded frame without QP to encode complete callback. QP should be
   // parsed and set.
   EncodedImage encoded_image;
@@ -8137,10 +8143,13 @@
   webrtc::test::ScopedFieldTrials field_trials(
       "WebRTC-QpParsingKillSwitch/Enabled/");
 
-  // Enable encoder source to force encoder reconfig.
-  encoder_factory_.SetHasInternalSource(true);
   ResetEncoder("VP8", 1, 1, 1, false);
 
+  // Force encoder reconfig.
+  video_source_.IncomingCapturedFrame(
+      CreateFrame(1, codec_width_, codec_height_));
+  video_stream_encoder_->WaitUntilTaskQueueIsIdle();
+
   EncodedImage encoded_image;
   encoded_image.qp_ = -1;
   encoded_image.SetEncodedData(EncodedImageBuffer::Create(