Collect data reduction proxy UMA on all platforms

UMA for the data reduction proxy was gated behind preprocessor
directives that resticted the logic to Android and iOS. This
change opens UMA calculations and collection up to all platforms.

BUG=369619

Review URL: https://codereview.chromium.org/266033002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@269026 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -545,9 +545,9 @@
       # Platform sends memory pressure signals natively.
       'native_memory_pressure_signals%': 0,
 
-      'data_reduction_fallback_host%' : '',
+      'data_reduction_fallback_host%' : 'http://compress.googlezip.net:80/',
       'data_reduction_dev_host%' : '',
-      'spdy_proxy_auth_origin%' : '',
+      'spdy_proxy_auth_origin%' : 'https://proxy.googlezip.net:443/',
       'spdy_proxy_auth_property%' : '',
       'spdy_proxy_auth_value%' : '',
       'data_reduction_proxy_probe_url%' : '',