Reland "Make webrtc_fuzzer_main depend on webrtc_component in Chromium."

This is a reland of 2148e9a931ea1a8a2ac0bfffd56e12370f8bf18c

Original change's description:
> Make webrtc_fuzzer_main depend on webrtc_component in Chromium.
>
> This is needed in order to land [1] and restrict visibility of some
> //third_party/webrtc_overrides targets.
>
> [1] - https://chromium-review.googlesource.com/c/chromium/src/+/1930801
>
> Bug: chromium:896154
> Change-Id: Ie71c44ee9a0203a85d77a1199acdcb8581dfb71b
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/160308
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#29875}

No-Try: True
No-Tree-Checks: true
TBR: kwiberg@webrtc.org
Bug: chromium:896154
Change-Id: I157bd4f90528a38ac16f17dd17af2f255dbd5ec9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/160401
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29888}

system_wrappers/BUILD.gn

@@ -96,6 +96,7 @@ rtc_library("field_trial") {
   deps = [
     "../rtc_base:checks",
     "../rtc_base:logging",
+    "../rtc_base/system:rtc_export",
     "//third_party/abseil-cpp/absl/strings",
   ]
 }
@@ -128,6 +129,7 @@ rtc_library("metrics") {
   deps = [
     "../rtc_base:checks",
     "../rtc_base:rtc_base_approved",
+    "../rtc_base/system:rtc_export",
   ]
 }
 

system_wrappers/include/field_trial.h

@@ -13,6 +13,8 @@
 
 #include <string>
 
+#include "rtc_base/system/rtc_export.h"
+
 // Field trials allow webrtc clients (such as Chrome) to turn on feature code
 // in binaries out in the field and gather information with that.
 //
@@ -61,7 +63,7 @@ namespace field_trial {
 // if the trial does not exists.
 //
 // Note: To keep things tidy append all the trial names with WebRTC.
-std::string FindFullName(const std::string& name);
+RTC_EXPORT std::string FindFullName(const std::string& name);
 
 // Convenience method, returns true iff FindFullName(name) return a string that
 // starts with "Enabled".
@@ -80,7 +82,7 @@ inline bool IsDisabled(const char* name) {
 // This method can be called at most once before any other call into webrtc.
 // E.g. before the peer connection factory is constructed.
 // Note: trials_string must never be destroyed.
-void InitFieldTrialsFromString(const char* trials_string);
+RTC_EXPORT void InitFieldTrialsFromString(const char* trials_string);
 
 const char* GetFieldTrialString();
 

system_wrappers/include/metrics.h

@@ -19,6 +19,7 @@
 
 #include "rtc_base/atomic_ops.h"
 #include "rtc_base/checks.h"
+#include "rtc_base/system/rtc_export.h"
 
 // Macros for allowing WebRTC clients (e.g. Chrome) to gather and aggregate
 // statistics.
@@ -253,29 +254,30 @@ class Histogram;
 // histogram).
 
 // Get histogram for counters.
-Histogram* HistogramFactoryGetCounts(const std::string& name,
-                                     int min,
-                                     int max,
-                                     int bucket_count);
+RTC_EXPORT Histogram* HistogramFactoryGetCounts(const std::string& name,
+                                                int min,
+                                                int max,
+                                                int bucket_count);
 
 // Get histogram for counters with linear bucket spacing.
-Histogram* HistogramFactoryGetCountsLinear(const std::string& name,
-                                           int min,
-                                           int max,
-                                           int bucket_count);
+RTC_EXPORT Histogram* HistogramFactoryGetCountsLinear(const std::string& name,
+                                                      int min,
+                                                      int max,
+                                                      int bucket_count);
 
 // Get histogram for enumerators.
 // |boundary| should be above the max enumerator sample.
-Histogram* HistogramFactoryGetEnumeration(const std::string& name,
-                                          int boundary);
+RTC_EXPORT Histogram* HistogramFactoryGetEnumeration(const std::string& name,
+                                                     int boundary);
 
 // Get sparse histogram for enumerators.
 // |boundary| should be above the max enumerator sample.
-Histogram* SparseHistogramFactoryGetEnumeration(const std::string& name,
-                                                int boundary);
+RTC_EXPORT Histogram* SparseHistogramFactoryGetEnumeration(
+    const std::string& name,
+    int boundary);
 
 // Function for adding a |sample| to a histogram.
-void HistogramAdd(Histogram* histogram_pointer, int sample);
+RTC_EXPORT void HistogramAdd(Histogram* histogram_pointer, int sample);
 
 struct SampleInfo {
   SampleInfo(const std::string& name, int min, int max, size_t bucket_count);

test/fuzzers/BUILD.gn

@@ -15,17 +15,12 @@ rtc_library("webrtc_fuzzer_main") {
     "webrtc_fuzzer_main.cc",
   ]
   deps = [
-    "../../rtc_base:rtc_base_approved",
     "//testing/libfuzzer:libfuzzer_main",
   ]
-
-  # When WebRTC fuzzer tests are built on Chromium bots they need to link
-  # with Chromium's implementation of metrics and field trial.
   if (build_with_chromium) {
-    deps += [
-      "../../../webrtc_overrides:field_trial",
-      "../../../webrtc_overrides:metrics",
-    ]
+    deps += [ "//third_party/webrtc_overrides:webrtc_component" ]
+  } else {
+    deps += [ "../../rtc_base:rtc_base_approved" ]
   }
 }