Enable Data Reduction Proxy (DRP) holdback by default

Bug: 1048736
Change-Id: I0550f8ba1e34a151a645c1bd2204dde1ad0fafbd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2115881
Auto-Submit: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#752542}

components/data_reduction_proxy/core/common/data_reduction_proxy_features.cc

@@ -22,7 +22,7 @@ const base::Feature kDogfood{"DataReductionProxyDogfood",
 // Does not affect the state of save-data header or other
 // features that may depend on data saver being enabled.
 const base::Feature kDataReductionProxyHoldback{
-    "DataReductionProxyHoldback", base::FEATURE_DISABLED_BY_DEFAULT};
+    "DataReductionProxyHoldback", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Enables data reduction proxy when network service is enabled.
 const base::Feature kDataReductionProxyEnabledWithNetworkService{