Clear browsing data from ContentSuggestionService only if exists.

components/ntp_snippets/ntp_snippets_service.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/ntp_snippets/ntp_snippets_service.h"
 
 #include <algorithm>
 #include <iterator>
 #include <utility>
 
@@ skipping 960 matching lines @@
 
   switch (state) {
     case State::NOT_INITED:
       // Initial state, it should not be possible to get back there.
       NOTREACHED();
       return;
 
     case State::READY: {
       DCHECK(state_ == State::NOT_INITED || state_ == State::DISABLED);
 
+      // TODO(jkrcal): fetching snippets automatically upon creation of this
+      // lazily created service can cause troubles, e.g. in unittests where
+      // network I/O is not allowed.
+      // Either add a DCHECK here that we actually are allowed to do network I/O
+      // or change the logic so that some explicit call is always needed for the
+      // network request.
       bool fetch_snippets =
           categories_[articles_category_].snippets.empty() || fetch_after_load_;
       DVLOG(1) << "Entering state: READY";
       state_ = State::READY;
       fetch_after_load_ = false;
       EnterStateEnabled(fetch_snippets);
       return;
     }
 
     case State::DISABLED:
@@ skipping 64 matching lines @@
 }
 
 NTPSnippetsService::CategoryContent::CategoryContent() = default;
 NTPSnippetsService::CategoryContent::CategoryContent(CategoryContent&&) =
     default;
 NTPSnippetsService::CategoryContent::~CategoryContent() = default;
 NTPSnippetsService::CategoryContent& NTPSnippetsService::CategoryContent::
 operator=(CategoryContent&&) = default;
 
 }  // namespace ntp_snippets