Fix WebRTC fuzzers tests in Chromium.

When WebRTC fuzzers tests are built on Chromium bots they need to link
with Chromium's implementation of metrics.

TBR=phoglund@webrtc.org

Bug: webrtc:9631
Change-Id: I1c955e646366b6b37d3ca595888e8cc94fe1b00e
Reviewed-on: https://webrtc-review.googlesource.com/100940
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Christian Fremerey <chfremer@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24771}

test/fuzzers/BUILD.gn

@@ -21,6 +21,12 @@ rtc_static_library("webrtc_fuzzer_main") {
     "../../system_wrappers:runtime_enabled_features_default",
     "//testing/libfuzzer:libfuzzer_main",
   ]
+
+  # When WebRTC fuzzer tests are built on Chromium bots they need to link
+  # with Chromium's implementation of metrics.
+  if (build_with_chromium) {
+    deps += [ "../../../webrtc_overrides:metrics" ]
+  }
 }
 
 rtc_static_library("fuzz_data_helper") {