Support server categories in NTPSnippetsService.

components/ntp_snippets/ntp_snippets_database.cc

Index: components/ntp_snippets/ntp_snippets_database.cc
diff --git a/components/ntp_snippets/ntp_snippets_database.cc b/components/ntp_snippets/ntp_snippets_database.cc
index 4b1427961588e4f70a4b0591d526aa3279479b0d..27f316a65fa31f2836537efbe3dd115d7a753d0c 100644
--- a/components/ntp_snippets/ntp_snippets_database.cc
+++ b/components/ntp_snippets/ntp_snippets_database.cc
@@ -97,15 +97,15 @@ void NTPSnippetsDatabase::DeleteSnippets(
   DeleteSnippetsImpl(std::move(keys_to_remove));
 }
 
-void NTPSnippetsDatabase::LoadImage(const std::string& snippet_id,
+void NTPSnippetsDatabase::LoadImage(const std::string& suggestion_id,
                                     const SnippetImageCallback& callback) {
   if (IsInitialized())
-    LoadImageImpl(snippet_id, callback);
+    LoadImageImpl(suggestion_id, callback);
   else
-    pending_image_callbacks_.emplace_back(snippet_id, callback);
+    pending_image_callbacks_.emplace_back(suggestion_id, callback);
 }
 
-void NTPSnippetsDatabase::SaveImage(const std::string& snippet_id,
+void NTPSnippetsDatabase::SaveImage(const std::string& suggestion_id,
                                     const std::string& image_data) {
   DCHECK(IsInitialized());
 
@@ -114,7 +114,7 @@ void NTPSnippetsDatabase::SaveImage(const std::string& snippet_id,
 
   std::unique_ptr<ImageKeyEntryVector> entries_to_save(
       new ImageKeyEntryVector());
-  entries_to_save->emplace_back(snippet_id, std::move(image_proto));
+  entries_to_save->emplace_back(suggestion_id, std::move(image_proto));
 
   image_database_->UpdateEntries(
       std::move(entries_to_save),
@@ -123,9 +123,9 @@ void NTPSnippetsDatabase::SaveImage(const std::string& snippet_id,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
-void NTPSnippetsDatabase::DeleteImage(const std::string& snippet_id) {
+void NTPSnippetsDatabase::DeleteImage(const std::string& suggestion_id) {
   DeleteImagesImpl(
-      base::WrapUnique(new std::vector<std::string>(1, snippet_id)));
+      base::WrapUnique(new std::vector<std::string>(1, suggestion_id)));
 }
 
 void NTPSnippetsDatabase::OnDatabaseInited(bool success) {
@@ -269,13 +269,12 @@ void NTPSnippetsDatabase::DeleteSnippetsImpl(
                                       weak_ptr_factory_.GetWeakPtr()));
 }
 
-void NTPSnippetsDatabase::LoadImageImpl(const std::string& snippet_id,
+void NTPSnippetsDatabase::LoadImageImpl(const std::string& suggestion_id,
                                         const SnippetImageCallback& callback) {
   DCHECK(IsInitialized());
   image_database_->GetEntry(
-      snippet_id,
-      base::Bind(&NTPSnippetsDatabase::OnImageDatabaseLoaded,
-                 weak_ptr_factory_.GetWeakPtr(), callback));
+      suggestion_id, base::Bind(&NTPSnippetsDatabase::OnImageDatabaseLoaded,
+                                weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void NTPSnippetsDatabase::DeleteImagesImpl(