Reland "Move allocation and rtp conversion logic out of payload router."

This reverts commit c2406e4eaf7703c6c64d21318186adda791e09fd.

Reason for revert: Reland by removing the conflict with the broken CL.

Original change's description:
> Revert "Move allocation and rtp conversion logic out of payload router."
> 
> This reverts commit 1da4d79ba3275b3fa48cad3b2c0949e0d3b7afe7.
> 
> Reason for revert: Need to revert https://webrtc-review.googlesource.com/c/src/+/88220
> 
> This causes a merge conflict. So need to revert this first.
> 
> Original change's description:
> > Move allocation and rtp conversion logic out of payload router.
> > 
> > Makes it easier to write tests, and allows for moving rtp module
> > ownership into the payload router in the future.
> > 
> > The RtpPayloadParams class is split into declaration and definition and
> > moved into separate files.
> > 
> > Bug: webrtc:9517
> > Change-Id: I8700628edff19abcacfe8d3a20e4ba7476f712ad
> > Reviewed-on: https://webrtc-review.googlesource.com/88564
> > Commit-Queue: Stefan Holmer <stefan@webrtc.org>
> > Reviewed-by: Sebastian Jansson <srte@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#23983}
> 
> TBR=sprang@webrtc.org,stefan@webrtc.org,srte@webrtc.org
> 
> Change-Id: I342c4bf483d975c87c706fe7f76f44e2dc60fe4c
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: webrtc:9517
> Reviewed-on: https://webrtc-review.googlesource.com/88821
> Reviewed-by: JT Teh <jtteh@webrtc.org>
> Commit-Queue: JT Teh <jtteh@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#23991}

TBR=sprang@webrtc.org,stefan@webrtc.org,srte@webrtc.org,lliuu@webrtc.org,jtteh@webrtc.org,tkchin@webrtc.org

Change-Id: I154145cdbc668feee86dbe78860147a6954fee6c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9517
Reviewed-on: https://webrtc-review.googlesource.com/89020
Commit-Queue: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23996}

api/video/test/BUILD.gn

@@ -0,0 +1,27 @@
+# Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+import("../../../webrtc.gni")
+
+rtc_source_set("rtc_api_video_unittests") {
+  testonly = true
+
+  sources = [
+    "video_bitrate_allocation_unittest.cc",
+  ]
+
+  if (!build_with_chromium && is_clang) {
+    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
+  }
+
+  deps = [
+    "..:video_bitrate_allocation",
+    "../../../test:test_support",
+  ]
+}

api/video/test/video_bitrate_allocation_unittest.cc

@@ -0,0 +1,63 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <memory>
+#include <string>
+
+#include "api/video/video_bitrate_allocation.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+TEST(VideoBitrateAllocation, SimulcastTargetBitrate) {
+  VideoBitrateAllocation bitrate;
+  bitrate.SetBitrate(0, 0, 10000);
+  bitrate.SetBitrate(0, 1, 20000);
+  bitrate.SetBitrate(1, 0, 40000);
+  bitrate.SetBitrate(1, 1, 80000);
+
+  VideoBitrateAllocation layer0_bitrate;
+  layer0_bitrate.SetBitrate(0, 0, 10000);
+  layer0_bitrate.SetBitrate(0, 1, 20000);
+
+  VideoBitrateAllocation layer1_bitrate;
+  layer1_bitrate.SetBitrate(0, 0, 40000);
+  layer1_bitrate.SetBitrate(0, 1, 80000);
+
+  std::vector<absl::optional<VideoBitrateAllocation>> layer_allocations =
+      bitrate.GetSimulcastAllocations();
+
+  EXPECT_EQ(layer0_bitrate, layer_allocations[0]);
+  EXPECT_EQ(layer1_bitrate, layer_allocations[1]);
+}
+
+TEST(VideoBitrateAllocation, SimulcastTargetBitrateWithInactiveStream) {
+  // Create bitrate allocation with bitrate only for the first and third stream.
+  VideoBitrateAllocation bitrate;
+  bitrate.SetBitrate(0, 0, 10000);
+  bitrate.SetBitrate(0, 1, 20000);
+  bitrate.SetBitrate(2, 0, 40000);
+  bitrate.SetBitrate(2, 1, 80000);
+
+  VideoBitrateAllocation layer0_bitrate;
+  layer0_bitrate.SetBitrate(0, 0, 10000);
+  layer0_bitrate.SetBitrate(0, 1, 20000);
+
+  VideoBitrateAllocation layer2_bitrate;
+  layer2_bitrate.SetBitrate(0, 0, 40000);
+  layer2_bitrate.SetBitrate(0, 1, 80000);
+
+  std::vector<absl::optional<VideoBitrateAllocation>> layer_allocations =
+      bitrate.GetSimulcastAllocations();
+
+  EXPECT_EQ(layer0_bitrate, layer_allocations[0]);
+  EXPECT_FALSE(layer_allocations[1]);
+  EXPECT_EQ(layer2_bitrate, layer_allocations[2]);
+}
+}  // namespace webrtc

api/video/video_bitrate_allocation.cc

@@ -107,6 +107,23 @@ std::vector<uint32_t> VideoBitrateAllocation::GetTemporalLayerAllocation(
   return temporal_rates;
 }
 
+std::vector<absl::optional<VideoBitrateAllocation>>
+VideoBitrateAllocation::GetSimulcastAllocations() const {
+  std::vector<absl::optional<VideoBitrateAllocation>> bitrates;
+  for (size_t si = 0; si < kMaxSpatialLayers; ++si) {
+    absl::optional<VideoBitrateAllocation> layer_bitrate;
+    if (IsSpatialLayerUsed(si)) {
+      layer_bitrate = VideoBitrateAllocation();
+      for (int tl = 0; tl < kMaxTemporalStreams; ++tl) {
+        if (HasBitrate(si, tl))
+          layer_bitrate->SetBitrate(0, tl, GetBitrate(si, tl));
+      }
+    }
+    bitrates.push_back(layer_bitrate);
+  }
+  return bitrates;
+}
+
 bool VideoBitrateAllocation::operator==(
     const VideoBitrateAllocation& other) const {
   for (size_t si = 0; si < kMaxSpatialLayers; ++si) {

api/video/video_bitrate_allocation.h

@@ -62,6 +62,12 @@ class VideoBitrateAllocation {
   // layer with a defined bitrate.
   std::vector<uint32_t> GetTemporalLayerAllocation(size_t spatial_index) const;
 
+  // Returns one VideoBitrateAllocation for each spatial layer. This is used to
+  // configure simulcast streams. Note that the length of the returned vector is
+  // always kMaxSpatialLayers, the optional is unset for unused layers.
+  std::vector<absl::optional<VideoBitrateAllocation>> GetSimulcastAllocations()
+      const;
+
   uint32_t get_sum_bps() const { return sum_; }  // Sum of all bitrates.
   uint32_t get_sum_kbps() const {
     // Round down to not exceed the allocated bitrate.