Revert "Relaxing no-streams presubmit check (streams are allowed in tests)."

This reverts commit 73ac90863d339599e6fc42fc5228282f479ebc0d.

Reason for revert: Sometimes 'gn refs' exits with status 1.

Original change's description:
> Relaxing no-streams presubmit check (streams are allowed in tests).
> 
> It is actually fine to use streams in testonly code. This CL relaxes
> the presubmit check in order allow streams usage in tests.
> 
> Bug: webrtc:8982
> Change-Id: I18bbf079e804815956cd94ac761cc13022c0761e
> No-Try: True
> Reviewed-on: https://webrtc-review.googlesource.com/61701
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
> Reviewed-by: Sebastian Jansson <srte@webrtc.org>
> Reviewed-by: Tomas Gunnarsson <tommi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#22482}

TBR=phoglund@webrtc.org,mbonadei@webrtc.org,tommi@webrtc.org,srte@webrtc.org,tommi@chromium.org

Change-Id: I053b953896ca66be26835b60fb245d5ac0832294
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:8982
Reviewed-on: https://webrtc-review.googlesource.com/62780
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22485}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 96cdbf1..e533507 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -410,10 +410,6 @@
 def CheckNoStreamUsageIsAdded(input_api, output_api,
                               error_formatter=_ReportErrorFileAndLineNumber):
   """Make sure that no more dependencies on stringstream are added."""
-  with _AddToPath(input_api.os_path.join(
-      input_api.PresubmitLocalPath(), 'tools_webrtc', 'presubmit_checks_lib')):
-    from gn_refs import DefaultGnProject, BelongsToTestTarget
-
   error_msg = ('Usage of <sstream>, <istream> and <ostream> in WebRTC is '
                'deprecated.\n'
                'This includes the following types:\n'
@@ -437,15 +433,13 @@
   usage_re = input_api.re.compile(r'std::(w|i|o|io|wi|wo|wio)(string)*stream')
   no_presubmit_re = input_api.re.compile(
       r'  // no-presubmit-check TODO\(webrtc:8982\)')
-  is_cpp_file = lambda f: f.LocalPath().endswith(('.cc', '.h'))
-  with DefaultGnProject() as out_dir:
-    for f in input_api.AffectedFiles(file_filter=is_cpp_file):
-      if BelongsToTestTarget(f.LocalPath(), out_dir):
-        continue
-      for line_num, line in f.ChangedContents():
-        if ((include_re.search(line) or usage_re.search(line))
-            and not no_presubmit_re.search(line)):
-          errors.append(error_formatter(f.LocalPath(), line_num))
+  for f in input_api.AffectedSourceFiles(input_api.FilterSourceFile):
+    if f.LocalPath() == 'PRESUBMIT.py':
+      continue
+    for line_num, line in f.ChangedContents():
+      if ((include_re.search(line) or usage_re.search(line))
+          and not no_presubmit_re.search(line)):
+        errors.append(error_formatter(f.LocalPath(), line_num))
   if errors:
     return [output_api.PresubmitError(error_msg, errors)]
   return []