bind-gen: Improve the progress print of the binding generator

Improves the progress print so that the intention will be
a little clearer; when the bindings code generation finishes,
leave the last message on the console.

When https://crrev.com/c/2081633 will land, the bindings code
generation will be very long (a few minutes).  It could make
Chromium developers wonder if a build completely stops.  Hope
that printing the progress would prevent such a concern.

Bug: 839389, 1108111
Change-Id: If556010d2d3469c5e0ded6d9b96fa6a5ffc26764
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2313816Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791764}

third_party/blink/renderer/bindings/scripts/generate_bindings.py

@@ -82,18 +82,21 @@ def main():
         dispatch_table[task](task_queue=task_queue,
                              web_idl_database=web_idl_database)
 
-    def report_progress(total, done):
+    def print_to_console(message):
         out = sys.stdout
         if not out.isatty():
             return
-        if total == 0:
-            return
-        percentage = int(float(done) / float(total) * 100)
-        message = "Blink-V8 bindings generation: {}% done\r".format(percentage)
         out.write(message)
         out.flush()
 
+    def report_progress(total, done):
+        percentage = (int(float(done) / float(total) *
+                          100) if total != 0 else 100)
+        message = "Blink-V8 bindings generation: {}% done\r".format(percentage)
+        print_to_console(message)
+
     task_queue.run(report_progress)
+    print_to_console("\n")
 
 
 if __name__ == '__main__':