Reland "Isolating APM API build target: making :api an actual target."

This reverts commit 61c6e5643e7ea058e653956980a90e033249c055.

Reason for revert: downstream projects prepared for this change

Original change's description:
> Revert "Isolating APM API build target: making :api an actual target."
> 
> This reverts commit a7f77a7c05b5d26520fd01a773ffb2c8b15b60ff.
> 
> Reason for revert: breaking downstream
> 
> Original change's description:
> > Isolating APM API build target: making :api an actual target.
> > 
> > This CL is part of a refactoring work to unblock other CLs
> > that would generate a circular dependency when including
> > modules/audio_processing. It will also allow to easily move
> > the APM interface part under //api.
> > 
> > More in detail, this change moves the APM interface files from
> > the build target modules/audio_processing to
> > modules/audio_processing:api. It also adds :api as dependency
> > where needed.
> > 
> > Bug: webrtc:9535
> > Change-Id: I72829e22d08ba4d75985f0421e6e8bf0216ebecd
> > Reviewed-on: https://webrtc-review.googlesource.com/c/109501
> > Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> > Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
> > Reviewed-by: Niels Moller <nisse@webrtc.org>
> > Reviewed-by: Sam Zackrisson <saza@webrtc.org>
> > Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#25539}
> 
> TBR=saza@webrtc.org,alessiob@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org,kthelgason@webrtc.org
> 
> Change-Id: I974c6237311e7c06970aa62e5f6940f3aa80113d
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: webrtc:9535
> Reviewed-on: https://webrtc-review.googlesource.com/c/109820
> Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
> Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#25540}

TBR=saza@webrtc.org,alessiob@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org,kthelgason@webrtc.org

Change-Id: Ic8ed4cc3baf43d639ce13cae256c007728c3ad92
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9535
Reviewed-on: https://webrtc-review.googlesource.com/c/109884
Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25547}

modules/audio_processing/BUILD.gn

@@ -38,13 +38,27 @@ rtc_static_library("config") {
   ]
 }
 
-# Temporary dummy target for the APM interface.
 rtc_source_set("api") {
   visibility = [ "*" ]
-
-  # TODO(bugs.webrtc.org/9535): Adapt downstream projects and populate.
-  sources = []
-  deps = []
+  sources = [
+    "include/audio_processing.cc",
+    "include/audio_processing.h",
+  ]
+  deps = [
+    ":audio_frame_view",
+    ":audio_generator_interface",
+    ":audio_processing_statistics",
+    ":config",
+    ":gain_control_interface",
+    "../../api/audio:aec3_config",
+    "../../api/audio:echo_control",
+    "../../rtc_base:deprecation",
+    "../../rtc_base:macromagic",
+    "../../rtc_base:ptr_util",
+    "../../rtc_base:rtc_base_approved",
+    "../../rtc_base/system:rtc_export",
+    "//third_party/abseil-cpp/absl/types:optional",
+  ]
 }
 
 rtc_static_library("audio_processing") {
@@ -76,11 +90,6 @@ rtc_static_library("audio_processing") {
     "gain_controller2.h",
     "include/aec_dump.cc",
     "include/aec_dump.h",
-
-    # TODO(bugs.webrtc.org/9535): Adapt downstream projects and remove
-    # include/audio_processing.cc/h.
-    "include/audio_processing.cc",
-    "include/audio_processing.h",
     "level_estimator_impl.cc",
     "level_estimator_impl.h",
     "low_cut_filter.cc",
@@ -333,6 +342,7 @@ if (rtc_include_tests) {
       "include/mock_audio_processing.h",
     ]
     deps = [
+      ":api",
       ":audio_processing",
       ":audio_processing_statistics",
       "../../test:test_support",
@@ -511,6 +521,7 @@ if (rtc_include_tests) {
     ]
 
     deps = [
+      ":api",
       ":audio_generator_factory",
       ":audio_processing",
       ":file_audio_generator",
@@ -555,6 +566,7 @@ if (rtc_include_tests) {
 
       deps = [
         ":analog_mic_simulation",
+        ":api",
         ":apm_logging",
         ":audio_processing",
         ":audioproc_debug_proto",
@@ -585,6 +597,7 @@ if (rtc_include_tests) {
         "test/audioproc_float_main.cc",
       ]
       deps = [
+        ":api",
         ":audio_processing",
         "../../api:audioproc_f_api",
         "../../rtc_base:rtc_base_approved",
@@ -610,6 +623,7 @@ if (rtc_include_tests) {
     ]
 
     deps = [
+      ":api",
       ":audio_processing",
       "../../api:array_view",
       "../../api/audio:audio_frame_api",
@@ -694,6 +708,7 @@ if (rtc_include_tests) {
       ]
 
       deps = [
+        ":api",
         ":audio_processing",
         ":audioproc_debug_proto",
         ":audioproc_protobuf_utils",

modules/audio_processing/aec_dump/BUILD.gn

@@ -43,6 +43,7 @@ rtc_source_set("mock_aec_dump_unittests") {
 
   deps = [
     ":mock_aec_dump",
+    "..:api",
     "../",
     "../../../rtc_base:rtc_base_approved",
     "//testing/gtest",