Revert of GN: Include webrtc/api targets even if rtc_include_tests=false (patchset #2 id:20001 of https://codereview.webrtc.org/2725053008/ )

Reason for revert:
Fails Chromium builds:
b/c/b/linux/src/buildtools/linux64/gn gen //out/Release --check
  -> returned 1
ERROR at //third_party/webrtc/api/BUILD.gn:186:5: Can't load input file.
    "//webrtc/test:test_support",
    ^-------------------------

Original issue's description:
> GN: Include webrtc/api targets even if rtc_include_tests=false
>
> The main purpose with the rtc_include_tests GN variable is to avoid
> generating and compiling all the test targets.
> Some of our examples have dependencies on the test headers in API,
> so therefore this change is relaxing that condition.
>
> BUG=webrtc:6828
> NOTRY=True
> TBR=ehmaldonado@webrtc.org,
>
> Review-Url: https://codereview.webrtc.org/2725053008
> Cr-Commit-Position: refs/heads/master@{#16989}
> Committed: https://chromium.googlesource.com/external/webrtc/+/a769ceba656eff1d12df82ef3058306cf948b215

TBR=ehmaldonado@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:6828

Review-Url: https://codereview.webrtc.org/2728073002
Cr-Commit-Position: refs/heads/master@{#16990}
diff --git a/webrtc/api/BUILD.gn b/webrtc/api/BUILD.gn
index a447dec..716f8c9 100644
--- a/webrtc/api/BUILD.gn
+++ b/webrtc/api/BUILD.gn
@@ -171,55 +171,55 @@
   }
 }
 
-rtc_source_set("mock_audio_mixer") {
-  testonly = true
-  sources = [
-    "test/mock_audio_mixer.h",
-  ]
-
-  public_deps = [
-    ":audio_mixer_api",
-  ]
-
-  deps = [
-    "//testing/gmock",
-    "//webrtc/test:test_support",
-  ]
-}
-
-rtc_source_set("libjingle_peerconnection_test_api") {
-  testonly = true
-  sources = [
-    "test/fakeconstraints.h",
-  ]
-
-  public_deps = [
-    ":libjingle_peerconnection_api",
-  ]
-
-  deps = [
-    "../base:rtc_base_approved",
-    "//webrtc/test:test_support",
-  ]
-}
-
-rtc_source_set("fakemetricsobserver") {
-  testonly = true
-  sources = [
-    "fakemetricsobserver.cc",
-    "fakemetricsobserver.h",
-  ]
-  deps = [
-    ":libjingle_peerconnection_api",
-    "../base:rtc_base_approved",
-  ]
-  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" ]
-  }
-}
-
 if (rtc_include_tests) {
+  rtc_source_set("mock_audio_mixer") {
+    testonly = true
+    sources = [
+      "test/mock_audio_mixer.h",
+    ]
+
+    public_deps = [
+      ":audio_mixer_api",
+    ]
+
+    deps = [
+      "//testing/gmock",
+      "//webrtc/test:test_support",
+    ]
+  }
+
+  rtc_source_set("libjingle_peerconnection_test_api") {
+    testonly = true
+    sources = [
+      "test/fakeconstraints.h",
+    ]
+
+    public_deps = [
+      ":libjingle_peerconnection_api",
+    ]
+
+    deps = [
+      "../base:rtc_base_approved",
+      "//webrtc/test:test_support",
+    ]
+  }
+
+  rtc_source_set("fakemetricsobserver") {
+    testonly = true
+    sources = [
+      "fakemetricsobserver.cc",
+      "fakemetricsobserver.h",
+    ]
+    deps = [
+      ":libjingle_peerconnection_api",
+      "../base:rtc_base_approved",
+    ]
+    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" ]
+    }
+  }
+
   rtc_source_set("rtc_api_unittests") {
     testonly = true
     sources = [