Tool added to extract network traffic annotations.

tools/traffic_annotation/README.txt

+This tool runs the clang tool for extraction of Network Traffic Annotations
+from chromium source code and collects and summarizes its outputs.
+
+Build:
+ninja -C [build directory] traffic_annotation_auditor
+
+Usage: 
+traffic_annotation_auditor [OPTION]... [path_filter]...
+Extracts network traffic annotations from source files. If path filter(s) are
+specified, only those directories of the source will be analyzed.
+
+Options:
+  -h, --help              Shows help.
+  --build_dir             Path to the build directory from which the
+                            annotations will be extracted.
+  --extractor_output_dir  Path to the directory that extracted
+                            partial files will be written to. Will
+                            be automatically generated and deleted
+                            if not specified.
+  --extracted_input_dir   Path to a directory where extracted
+                            partial annotations are already stored.
+                            If specified, build directory will be
+                            ignored.
+  --summary_file          Path to an output file with summary of
+                            extracted annotations.
+Example:
+  traffic_annotation_auditor --build_dir=out/Debug
+    --summary_file=report.txt
+
+
+To run on Windows:
+Before running the program as above, you should build COMPLETE chromium with
+clang with keeprsp switch as follows:
+1. gn args [build_dir, e.g. out\Debug]
+2. add is_clang=true to the opened text file and save and close it.
+3. ninja -C [build_dir] -d keeprsp -k 1000