Revert of Make it possible for tests to set up trace event handlers. (patchset #4 id:60001 of https://codereview.webrtc.org/3002663002/ )

Reason for revert:
Breaks Chromium bots.
https://build.chromium.org/p/chromium.webrtc.fyi/builders/Mac%20Builder/builds/27340/steps/generate_build_files/logs/stdio

Original issue's description:
> Make it possible for tests to set up trace event handlers.
>
> As it is now, the first time a TRACE_EVENT... is called, the result from
> the current handler is stored in a static const variable, and subsequent
> calls will use that value regardless of changes to the handler.
>
> This is a problem if a test wants to use another handler.
>
> BUG=None
>
> Review-Url: https://codereview.webrtc.org/3002663002
> Cr-Commit-Position: refs/heads/master@{#19382}
> Committed: a973265622

TBR=hbos@webrtc.org,kwiberg@webrtc.org,mbonadei@webrtc.org,kjellander@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None

Review-Url: https://codereview.webrtc.org/2997963002
Cr-Commit-Position: refs/heads/master@{#19383}

webrtc/BUILD.gn

@@ -26,17 +26,6 @@ config("common_inherited_config") {
   if (build_with_mozilla) {
     defines += [ "WEBRTC_MOZILLA_BUILD" ]
   }
-  # Some tests need to declare their own trace event handlers. If this define is
-  # not set, the first time TRACE_EVENT_* is called it will store the return
-  # value for the current handler in an static variable, so that subsequent
-  # changes to the handler for that TRACE_EVENT_* will be ignored.
-  # So when tests are included, we set this define, making it possible to use
-  # different event handlers in different tests.
-  if (rtc_include_tests) {
-    defines += [ "WEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS=1" ]
-  } else {
-    defines += [ "WEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS=0" ]
-  }
   if (build_with_chromium) {
     defines = [
       # TODO(kjellander): Cleanup unused ones and move defines closer to

webrtc/rtc_base/trace_event.h

@@ -575,15 +575,9 @@
 #define INTERNAL_TRACE_EVENT_UID(name_prefix) \
     INTERNAL_TRACE_EVENT_UID2(name_prefix, __LINE__)
 
-#if WEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS
-#define INTERNAL_TRACE_EVENT_INFO_TYPE const unsigned char*
-#else
-#define INTERNAL_TRACE_EVENT_INFO_TYPE static const unsigned char*
-#endif  // WEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS
-
 // Implementation detail: internal macro to create static category.
 #define INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category) \
-    INTERNAL_TRACE_EVENT_INFO_TYPE INTERNAL_TRACE_EVENT_UID(catstatic) = \
+    static const unsigned char* INTERNAL_TRACE_EVENT_UID(catstatic) = \
         TRACE_EVENT_API_GET_CATEGORY_ENABLED(category);
 
 // Implementation detail: internal macro to create static category and add