Moving previews code from components/ to chrome/

chrome/browser/previews/previews_service.cc

 // Copyright 2016 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 "chrome/browser/previews/previews_service.h"
 
+#include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/memory/ptr_util.h"
 #include "base/sequenced_task_runner.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/common/chrome_constants.h"
+#include "components/data_reduction_proxy/core/common/data_reduction_proxy_params.h"
+#include "components/previews/core/previews_experiments.h"
 #include "components/previews/core/previews_io_data.h"
 #include "components/previews/core/previews_opt_out_store.h"
 #include "components/previews/core/previews_opt_out_store_sql.h"
 #include "components/previews/core/previews_ui_service.h"
 #include "content/public/browser/browser_thread.h"
 
+namespace {
+
+// Returns true if the field trial that should enable previews for |type| for
+// prohibitvely slow networks is active.

[tbansal1, 2017/03/10 21:14:53]

This comment looks incorrect.

Or may be change the function name to be more descriptive.

[RyanSturm, 2017/03/10 22:06:29]

Done.

+bool IsPreviewsTypeEnabled(previews::PreviewsType type) {
+  switch (type) {
+    case previews::PreviewsType::OFFLINE:
+      return previews::params::IsOfflinePreviewsEnabled();
+    case previews::PreviewsType::NONE:
+    case previews::PreviewsType::LAST:
+      break;
+  }
+  NOTREACHED();
+  return false;
+}
+
+// Returns the version of preview treatment |type|. Should default to 0 if not

[tbansal1, 2017/03/10 21:14:53]

s/Should default/Defaults/

[RyanSturm, 2017/03/10 22:06:29]

Done.

+// specified in field trial config.
+int GetPreviewsTypeVersion(previews::PreviewsType type) {
+  switch (type) {
+    case previews::PreviewsType::OFFLINE:
+      return previews::params::OfflinePreviewsVersion();
+    case previews::PreviewsType::NONE:
+    case previews::PreviewsType::LAST:
+      break;
+  }
+  NOTREACHED();
+  return -1;
+}
+
+// Returns the enabled PreviewsTypes with their version.
+std::unique_ptr<previews::PreviewsTypeList> GetEnabledPreviews() {
+  std::unique_ptr<previews::PreviewsTypeList> enabled_previews(
+      new previews::PreviewsTypeList());
+
+  // Loop across all previews types (relies on sequential enum values).
+  for (int i = static_cast<int>(previews::PreviewsType::NONE) + 1;
+       i < static_cast<int>(previews::PreviewsType::LAST); ++i) {
+    previews::PreviewsType type = static_cast<previews::PreviewsType>(i);
+    if (IsPreviewsTypeEnabled(type)) {

[tbansal1, 2017/03/10 21:14:53]

rm parens.

[RyanSturm, 2017/03/10 22:06:29]

Done.

+      enabled_previews->push_back({type, GetPreviewsTypeVersion(type)});
+    }
+  }
+  return enabled_previews;
+}
+
+}  // namespace
+
 PreviewsService::PreviewsService() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 }
 
 PreviewsService::~PreviewsService() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 }
 
 void PreviewsService::Initialize(
     previews::PreviewsIOData* previews_io_data,
     const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
     const base::FilePath& profile_path) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   base::SequencedWorkerPool* blocking_pool =
       content::BrowserThread::GetBlockingPool();
   // Get the background thread to run SQLite on.
   scoped_refptr<base::SequencedTaskRunner> background_task_runner =
       blocking_pool->GetSequencedTaskRunner(blocking_pool->GetSequenceToken());
 
   previews_ui_service_ = base::MakeUnique<previews::PreviewsUIService>(
       previews_io_data, io_task_runner,
       base::MakeUnique<previews::PreviewsOptOutStoreSQL>(
           io_task_runner, background_task_runner,
-          profile_path.Append(chrome::kPreviewsOptOutDBFilename)));
+          profile_path.Append(chrome::kPreviewsOptOutDBFilename),
+          GetEnabledPreviews()),
+      base::Bind(&IsPreviewsTypeEnabled));
 }