Replace remaining gflags usages with rtc_base/flags

Continued from https://codereview.webrtc.org/2995363002

BUG=webrtc:7644

Review-Url: https://codereview.webrtc.org/3005483002
Cr-Commit-Position: refs/heads/master@{#19624}
diff --git a/webrtc/modules/audio_coding/BUILD.gn b/webrtc/modules/audio_coding/BUILD.gn
index abe064f..50819f1 100644
--- a/webrtc/modules/audio_coding/BUILD.gn
+++ b/webrtc/modules/audio_coding/BUILD.gn
@@ -1395,7 +1395,6 @@
       "../../test:test_support",
       "../rtp_rtcp",
       "//testing/gtest",
-      "//third_party/gflags:gflags",
     ]
   }  # delay_test
 
@@ -1425,7 +1424,6 @@
       "../../test:test_support",
       "../rtp_rtcp",
       "//testing/gtest",
-      "//third_party/gflags:gflags",
     ]
   }  # insert_packet_with_timing
 
@@ -1520,7 +1518,6 @@
         "../../rtc_base:rtc_base_approved",
         "../../system_wrappers:system_wrappers_default",
         "../../test:test_support",
-        "//third_party/gflags",
       ]
     }
   }
@@ -1792,9 +1789,9 @@
       ":neteq",
       ":neteq_test_tools",
       ":pcm16b",
+      "../../rtc_base:rtc_base_approved",
       "../../system_wrappers:system_wrappers_default",
       "//testing/gtest",
-      "//third_party/gflags:gflags",
     ]
 
     if (!build_with_chromium && is_clang) {
@@ -1832,9 +1829,9 @@
       ":neteq",
       ":neteq_test_support",
       "../..:webrtc_common",
+      "../../rtc_base:rtc_base_approved",
       "../../system_wrappers:system_wrappers_default",
       "../../test:test_support",
-      "//third_party/gflags",
     ]
   }