Show client placeholders for Server LoFi images.

content/child/runtime_features.cc

Index: content/child/runtime_features.cc
diff --git a/content/child/runtime_features.cc b/content/child/runtime_features.cc
index d80a199c0a39673673d21c3a50f679806c8ea4a9..8affb3fe8197f4fb4f3d9e879a2cfcf06e0157dc 100644
--- a/content/child/runtime_features.cc
+++ b/content/child/runtime_features.cc
@@ -9,6 +9,7 @@
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/metrics/field_trial.h"
+#include "base/metrics/field_trial_params.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "build/build_config.h"
@@ -390,6 +391,10 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
   WebRuntimeFeatures::EnableModuleScripts(
       base::FeatureList::IsEnabled(features::kModuleScripts));
 
+  WebRuntimeFeatures::EnableClientPlaceholdersForServerLoFi(
+      base::GetFieldTrialParamValue("PreviewsClientLoFi",
+                                    "replace_server_placeholders") == "true");
+
   // Enable explicitly enabled features, and then disable explicitly disabled
   // ones.
   if (command_line.HasSwitch(switches::kEnableBlinkFeatures)) {