[WebLayer] Implement ContentClient::GetLocalizedString

This makes it so various inputs (e.g. file input, submit button) have
the correct labels.

Change-Id: I5d49dc5d2d71a92fedfd0a6748ad142454e0e55a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1856845Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705274}

weblayer/common/content_client_impl.cc

@@ -16,6 +16,16 @@ ContentClientImpl::ContentClientImpl() {}
 
 ContentClientImpl::~ContentClientImpl() {}
 
+base::string16 ContentClientImpl::GetLocalizedString(int message_id) {
+  return l10n_util::GetStringUTF16(message_id);
+}
+
+base::string16 ContentClientImpl::GetLocalizedString(
+    int message_id,
+    const base::string16& replacement) {
+  return l10n_util::GetStringFUTF16(message_id, replacement);
+}
+
 base::StringPiece ContentClientImpl::GetDataResource(
     int resource_id,
     ui::ScaleFactor scale_factor) {

weblayer/common/content_client_impl.h

@@ -14,6 +14,9 @@ class ContentClientImpl : public content::ContentClient {
   ContentClientImpl();
   ~ContentClientImpl() override;
 
+  base::string16 GetLocalizedString(int message_id) override;
+  base::string16 GetLocalizedString(int message_id,
+                                    const base::string16& replacement) override;
   base::StringPiece GetDataResource(int resource_id,
                                     ui::ScaleFactor scale_factor) override;
   base::RefCountedMemory* GetDataResourceBytes(int resource_id) override;