tracing: remove WatchEvent feature

components/tracing/common/tracing_messages.h

Index: components/tracing/common/tracing_messages.h
diff --git a/components/tracing/common/tracing_messages.h b/components/tracing/common/tracing_messages.h
index 470339a92baf6583113ecfcdd35642d7b24f7406..3b7d7258e693952243d6fd06922f01d2dd99ae31 100644
--- a/components/tracing/common/tracing_messages.h
+++ b/components/tracing/common/tracing_messages.h
@@ -60,14 +60,6 @@ IPC_MESSAGE_CONTROL0(TracingMsg_CancelTracing)
 // Sent to all child processes to get trace buffer fullness.
 IPC_MESSAGE_CONTROL0(TracingMsg_GetTraceLogStatus)
 
-// Sent to all child processes to set watch event.
-IPC_MESSAGE_CONTROL2(TracingMsg_SetWatchEvent,
-                     std::string /* category_name */,
-                     std::string /* event_name */)
-
-// Sent to all child processes to clear watch event.
-IPC_MESSAGE_CONTROL0(TracingMsg_CancelWatchEvent)
-
 // Sent to all child processes to request a local (current process) memory dump.
 IPC_MESSAGE_CONTROL1(TracingMsg_ProcessMemoryDumpRequest,
                      base::trace_event::MemoryDumpRequestArgs)
@@ -87,9 +79,6 @@ IPC_MESSAGE_CONTROL4(TracingMsg_SetUMACallback,
 IPC_MESSAGE_CONTROL1(TracingMsg_ClearUMACallback,
                      std::string /* histogram_name */)
 
-// Sent everytime when a watch event is matched.
-IPC_MESSAGE_CONTROL0(TracingHostMsg_WatchEventMatched)
-
 // Notify the browser that this child process supports tracing.
 IPC_MESSAGE_CONTROL0(TracingHostMsg_ChildSupportsTracing)