Add support to previews/ for Server LoFi and LitePages

components/previews/core/previews_io_data.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 "components/previews/core/previews_io_data.h"
 
+#include <string>

[tbansal1, 2017/05/02 21:49:31]

This is already included in the header file, so it might not be needed here.

[RyanSturm, 2017/05/02 22:57:19]

Done.

+
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_path.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
-#include "base/metrics/histogram_macros.h"
+#include "base/metrics/histogram.h"
 #include "base/sequenced_task_runner.h"
 #include "base/time/default_clock.h"
 #include "components/previews/core/previews_black_list.h"
+#include "components/previews/core/previews_experiments.h"
 #include "components/previews/core/previews_opt_out_store.h"
 #include "components/previews/core/previews_ui_service.h"
 #include "net/base/load_flags.h"
 #include "net/nqe/network_quality_estimator.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
 #include "url/gurl.h"
 
 namespace previews {
 
 namespace {
 
 void LogPreviewsEligibilityReason(PreviewsEligibilityReason status,
                                   PreviewsType type) {
-  switch (type) {
-    case PreviewsType::OFFLINE:
-      UMA_HISTOGRAM_ENUMERATION(
-          "Previews.EligibilityReason.Offline", static_cast<int>(status),
-          static_cast<int>(PreviewsEligibilityReason::LAST));
-      break;
-    case PreviewsType::CLIENT_LOFI:
-      UMA_HISTOGRAM_ENUMERATION(
-          "Previews.EligibilityReason.ClientLoFi", static_cast<int>(status),
-          static_cast<int>(PreviewsEligibilityReason::LAST));
-      break;
-    default:
-      NOTREACHED();
-  }
+  std::string histogram_name("Previews.EligibilityReason.");
+  histogram_name.append(GetStringNameForType(type));

[tbansal1, 2017/05/02 21:49:31]

same here.
Use StringPiece of Printf as mentioned elsewhere.

[RyanSturm, 2017/05/02 22:57:19]

Done.

+  int32_t max_limit = static_cast<int32_t>(PreviewsEligibilityReason::LAST);
+
+  base::LinearHistogram::FactoryGet(
+      histogram_name, 0, max_limit, max_limit + 1,

[tbansal1, 2017/05/02 21:49:31]

min_bucket should be >= 1.
https://cs.chromium.org/chromium/src/base/metrics/histogram.h?rcl=9d3c221bdef...

[RyanSturm, 2017/05/02 22:57:19]

Done.

+      base::HistogramBase::kUmaTargetedHistogramFlag)
+      ->Add(static_cast<int>(status));
 }
 
 net::EffectiveConnectionType GetEffectiveConnectionTypeThresholdForPreviewsType(
     PreviewsType type) {
   switch (type) {
+    // These types check network qualtiy on their own.

[tbansal1, 2017/05/02 21:49:31]

typo in quality.

[RyanSturm, 2017/05/02 22:57:19]

Done.

+    case PreviewsType::LITE_PAGE:
+    case PreviewsType::SERVER_LOFI:
+      return net::EFFECTIVE_CONNECTION_TYPE_4G;
     case PreviewsType::OFFLINE:
       return params::EffectiveConnectionTypeThresholdForOffline();
     case PreviewsType::CLIENT_LOFI:
       return params::EffectiveConnectionTypeThresholdForClientLoFi();
     case PreviewsType::NONE:
     case PreviewsType::LAST:
       break;
   }
   NOTREACHED();
   return net::EFFECTIVE_CONNECTION_TYPE_UNKNOWN;
 }
 
+bool AllowedOnReload(PreviewsType type) {
+  switch (type) {
+    // These types return new content on refresh.
+    case PreviewsType::LITE_PAGE:
+    case PreviewsType::SERVER_LOFI:
+    case PreviewsType::CLIENT_LOFI:
+      return true;
+    // Loading these types will always be stale when refreshed.
+    case PreviewsType::OFFLINE:
+      return false;
+    case PreviewsType::NONE:
+    case PreviewsType::LAST:
+      break;
+  }
+  NOTREACHED();
+  return false;
+}
+
 }  // namespace
 
 PreviewsIOData::PreviewsIOData(
     const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner,
     const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner)
     : ui_task_runner_(ui_task_runner),
       io_task_runner_(io_task_runner),
       weak_factory_(this) {}
 
 PreviewsIOData::~PreviewsIOData() {}
@@ skipping 41 matching lines @@
                                         PreviewsType type) const {
   if (is_enabled_callback_.is_null() || !previews_black_list_) {
     LogPreviewsEligibilityReason(
         PreviewsEligibilityReason::BLACKLIST_UNAVAILABLE, type);
     return false;
   }
   if (!is_enabled_callback_.Run(type))
     return false;
 
   // The blacklist will disallow certain hosts for periods of time based on
-  // user's opting out of the preview
+  // user's opting out of the preview.
   PreviewsEligibilityReason status =
       previews_black_list_->IsLoadedAndAllowed(request.url(), type);
   if (status != PreviewsEligibilityReason::ALLOWED) {
     LogPreviewsEligibilityReason(status, type);
     return false;
   }
   net::NetworkQualityEstimator* network_quality_estimator =
       request.context()->network_quality_estimator();
   if (!network_quality_estimator ||
       network_quality_estimator->GetEffectiveConnectionType() <
           net::EFFECTIVE_CONNECTION_TYPE_OFFLINE) {
     LogPreviewsEligibilityReason(
         PreviewsEligibilityReason::NETWORK_QUALITY_UNAVAILABLE, type);
     return false;
   }
 
   if (network_quality_estimator->GetEffectiveConnectionType() >
       GetEffectiveConnectionTypeThresholdForPreviewsType(type)) {
     LogPreviewsEligibilityReason(PreviewsEligibilityReason::NETWORK_NOT_SLOW,
                                  type);
     return false;
   }
   // LOAD_VALIDATE_CACHE or LOAD_BYPASS_CACHE mean the user reloaded the page.
   // If this is a query for offline previews, reloads should be disallowed.
-  if (type == PreviewsType::OFFLINE &&
-      (request.load_flags() &
-       (net::LOAD_VALIDATE_CACHE | net::LOAD_BYPASS_CACHE))) {
-    LogPreviewsEligibilityReason(
-        PreviewsEligibilityReason::RELOAD_DISALLOWED_FOR_OFFLINE, type);
+  if (!AllowedOnReload(type) &&
+      request.load_flags() &
+          (net::LOAD_VALIDATE_CACHE | net::LOAD_BYPASS_CACHE)) {
+    LogPreviewsEligibilityReason(PreviewsEligibilityReason::RELOAD_DISALLOWED,
+                                 type);
     return false;
   }
+
   LogPreviewsEligibilityReason(PreviewsEligibilityReason::ALLOWED, type);
   return true;
 }
 
 }  // namespace previews