Reland "Enable the clang style plugin in rtc_base/"

This is a reland of Id63f0deb7b335690157ab157c35177b7836688da.

Original change's description:
> Enable the clang style plugin in rtc_base/
> 
> Enabled the plugin and cleaned up all issues it found.
> 
> Bug: webrtc:163
> Change-Id: Id63f0deb7b335690157ab157c35177b7836688da
> Reviewed-on: https://webrtc-review.googlesource.com/14660
> Commit-Queue: Steve Anton <steveanton@webrtc.org>
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#20401}

Bug: webrtc:163
Change-Id: I861a5fe741215115b0e7a2be9c0786836ff5376e
Reviewed-on: https://webrtc-review.googlesource.com/15040
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20416}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 710de7a..8490a60 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -716,10 +716,6 @@
     defines += [ "timezone=_timezone" ]
     sources -= [ "ifaddrs_converter.cc" ]
   }
-  if (is_win && is_clang) {
-    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
-    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
-  }
 }
 
 rtc_source_set("gtest_prod") {
@@ -752,6 +748,7 @@
     "fakeclock.cc",
     "fakeclock.h",
     "fakenetwork.h",
+    "fakesslidentity.cc",
     "fakesslidentity.h",
     "firewallsocketserver.cc",
     "firewallsocketserver.h",
@@ -782,7 +779,9 @@
     "testbase64.h",
     "testclient.cc",
     "testclient.h",
+    "testechoserver.cc",
     "testechoserver.h",
+    "testutils.cc",
     "testutils.h",
     "timedelta.h",
     "virtualsocketserver.cc",
@@ -799,11 +798,6 @@
     "//testing/gmock",
     "//testing/gtest",
   ]
-
-  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) {
@@ -825,11 +819,6 @@
       "//testing/gmock",
       "//testing/gtest",
     ]
-
-    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_base_nonparallel_tests") {
@@ -862,11 +851,6 @@
     if (is_win) {
       sources += [ "win32socketserver_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" ]
-    }
   }
 
   rtc_source_set("rtc_base_approved_unittests") {
@@ -931,10 +915,6 @@
       "../system_wrappers:system_wrappers",
       "../test:test_support",
     ]
-    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_task_queue_unittests") {
@@ -957,10 +937,6 @@
       ":rtc_task_queue",
       "../test:test_support",
     ]
-    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("sequenced_task_checker_unittests") {
@@ -1096,10 +1072,6 @@
       ":rtc_base",
     ]
     configs += [ ":rtc_base_unittests_config" ]
-    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 (build_with_chromium) {
       include_dirs = [ "../../boringssl/src/include" ]
     }