Use explicit WebString conversions in remaining content files

content/public/common/window_container_type.cc

Index: content/public/common/window_container_type.cc
diff --git a/content/public/common/window_container_type.cc b/content/public/common/window_container_type.cc
index 57291bb8a8d4ec54a4f00b334e11b8a8d603cf2f..265e371ca163224d776904a733f49cb6ec8e73d0 100644
--- a/content/public/common/window_container_type.cc
+++ b/content/public/common/window_container_type.cc
@@ -31,11 +31,14 @@ WindowContainerType WindowFeaturesToContainerType(
   bool persistent = false;
 
   for (size_t i = 0; i < window_features.additionalFeatures.size(); ++i) {
-    base::string16 feature = window_features.additionalFeatures[i];
-    if (base::LowerCaseEqualsASCII(feature, kBackground))
-      background = true;
-    else if (base::LowerCaseEqualsASCII(feature, kPersistent))
-      persistent = true;
+    blink::WebString feature = window_features.additionalFeatures[i];
+    if (feature.containsOnlyASCII()) {
+      std::string featureASCII = feature.ascii();
+      if (base::LowerCaseEqualsASCII(featureASCII, kBackground))
+        background = true;
+      else if (base::LowerCaseEqualsASCII(featureASCII, kPersistent))
+        persistent = true;
+    }
   }
 
   if (background) {