Add the latest version of Gmail

The following changes was made to the Proguard configuration for R8
processing to succeed:

1. Added the line -dontwarn sun.net.spi.nameservice.NameServiceDescriptor
2. Removed Signature from -keepattributes
3. Uncommented -verbose
4. Uncommented all -checkdiscard rules

Change-Id: Ie28fe241b7d378b74254cf22b705d0e264d9ed8c
diff --git a/tools/run_r8_on_app.py b/tools/run_r8_on_app.py
index 804a27e..19696bb 100755
--- a/tools/run_r8_on_app.py
+++ b/tools/run_r8_on_app.py
@@ -10,9 +10,10 @@
 
 import gmscore_data
 import youtube_data
+import gmail_data
 
 TYPES = ['dex', 'deploy', 'proguarded']
-APPS = ['gmscore', 'youtube']
+APPS = ['gmscore', 'youtube', 'gmail']
 
 def ParseOptions():
   result = optparse.OptionParser()
@@ -69,6 +70,9 @@
   elif options.app == 'youtube':
     options.version = options.version or '12.22'
     data = youtube_data
+  elif options.app == 'gmail':
+    options.version = options.version or '170604.16'
+    data = gmail_data
   else:
     raise 'Unexpected'