chore: delete unused content_tracing.idl (#30554)

shell/browser/api/content_tracing.idl

-enum RecordingMode { "record-until-full", "record-continuously", "record-as-much-as-possible", "trace-to-console" };
-
-dictionary TraceConfig {
-  Recordingmode recording_mode;
-  unsigned long trace_buffer_size_in_kb;
-  unsigned long trace_buffer_size_in_events;
-  boolean enable_argument_filter;
-  sequence<DOMString> included_categories;
-  sequence<DOMString> excluded_categories;
-  sequence<unsigned short> included_process_ids;
-  sequence<DOMString> histogram_names;
-  object memory_dump_config;
-};
-
-dictionary TraceCategoriesAndOptions {
-  DOMString categoryFilter;
-  DOMString traceOptions;
-};
-
-interface ContentTracing {
-  Promise<sequence<DOMString>> getCategories();
-  Promise<void> startRecording(TraceConfig config);
-  Promise<void> startRecording(TraceCategoriesAndOptions categoriesAndOptions);
-  Promise<DOMString> stopRecording(optional DOMString resultFilePath);
-  Promise<TraceBufferUsage> getTraceBufferUsage();
-};