Add explicit conversions methods for WebString <-> string16

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index 1f401ec96bd692ca5f1e8b7104fa8c8de3624ecf..4d7b82023f6423ac6dec61e4dec06db918251837 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -687,12 +687,14 @@ WebString BlinkPlatformImpl::queryLocalizedString(
   int message_id = ToMessageID(name);
   if (message_id < 0)
     return WebString();
-  return GetContentClient()->GetLocalizedString(message_id);
+  return WebString::fromUTF16(
+      GetContentClient()->GetLocalizedString(message_id));
 }
 
 WebString BlinkPlatformImpl::queryLocalizedString(
     WebLocalizedString::Name name, int numeric_value) {
-  return queryLocalizedString(name, base::IntToString16(numeric_value));
+  return queryLocalizedString(
+      name, WebString::fromUTF16(base::IntToString16(numeric_value)));
 }
 
 WebString BlinkPlatformImpl::queryLocalizedString(
@@ -700,8 +702,8 @@ WebString BlinkPlatformImpl::queryLocalizedString(
   int message_id = ToMessageID(name);
   if (message_id < 0)
     return WebString();
-  return base::ReplaceStringPlaceholders(
-      GetContentClient()->GetLocalizedString(message_id), value, NULL);
+  return WebString::fromUTF16(base::ReplaceStringPlaceholders(
+      GetContentClient()->GetLocalizedString(message_id), value.utf16(), NULL));
 }
 
 WebString BlinkPlatformImpl::queryLocalizedString(
@@ -713,10 +715,10 @@ WebString BlinkPlatformImpl::queryLocalizedString(
     return WebString();
   std::vector<base::string16> values;
   values.reserve(2);
-  values.push_back(value1);
-  values.push_back(value2);
-  return base::ReplaceStringPlaceholders(
-      GetContentClient()->GetLocalizedString(message_id), values, NULL);
+  values.push_back(value1.utf16());
+  values.push_back(value2.utf16());
+  return WebString::fromUTF16(base::ReplaceStringPlaceholders(
+      GetContentClient()->GetLocalizedString(message_id), values, NULL));
 }
 
 blink::WebThread* BlinkPlatformImpl::compositorThread() const {