Creates the shell for PreviewsOnePlatformHintsFetcher and implements …

…a private method CreateGetHintsRequestFromHosts.

PreviewsOnePlatformHintsFetcher provides the functionality for handling
the SimpleURLLoader request to the Optimization Guide Service for
OnePlatform hints to be requested based on individual users.


Bug: 932707
Change-Id: Ib3ee6b5bccf82870d196253b48f5961ddd4054d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1506532
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Michael Crouse <mcrouse@chromium.org>
Auto-Submit: Michael Crouse <mcrouse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638831}

components/previews/content/BUILD.gn

@@ -9,6 +9,8 @@ static_library("content") {
     "hint_cache_leveldb_store.cc",
     "hint_cache_leveldb_store.h",
     "hint_cache_store.h",
+    "hints_fetcher.cc",
+    "hints_fetcher.h",
     "previews_decider_impl.cc",
     "previews_decider_impl.h",
     "previews_hints.cc",

components/previews/content/hints_fetcher.cc

@@ -0,0 +1,63 @@
+// Copyright 2019 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/content/hints_fetcher.h"
+
+#include "base/feature_list.h"
+#include "base/metrics/histogram_macros.h"
+#include "components/optimization_guide/proto/hints.pb.h"
+#include "components/previews/content/hint_cache.h"
+#include "components/previews/core/previews_experiments.h"
+
+namespace previews {
+
+HintsFetcher::HintsFetcher(HintCache* hint_cache) : hint_cache_(hint_cache) {}
+
+HintsFetcher::~HintsFetcher() {}
+
+void HintsFetcher::FetchHintsForHosts(const std::vector<std::string>& hosts) {
+  SEQUENCE_CHECKER(sequence_checker_);
+
+  GetRemoteHints(hosts);
+}
+
+void HintsFetcher::GetRemoteHints(const std::vector<std::string>& hosts) {
+  get_hints_request_ =
+      std::make_unique<optimization_guide::proto::GetHintsRequest>();
+
+  // Add all the optimizations supported by the current version of Chrome,
+  // regardless of whether the session is in holdback for either of them.
+  get_hints_request_->add_supported_optimizations(
+      optimization_guide::proto::NOSCRIPT);
+  get_hints_request_->add_supported_optimizations(
+      optimization_guide::proto::RESOURCE_LOADING);
+  static_assert(static_cast<int>(PreviewsType::LITE_PAGE_REDIRECT) + 1 ==
+                    static_cast<int>(PreviewsType::LAST),
+                "PreviewsType has been updated, make sure OnePlatform hints "
+                "are not affected");
+
+  get_hints_request_->set_context(
+      optimization_guide::proto::CONTEXT_BATCH_UPDATE);
+
+  for (const auto& host : hosts) {
+    optimization_guide::proto::HostInfo* host_info =
+        get_hints_request_->add_hosts();
+    host_info->set_host(host);
+  }
+}
+
+void HintsFetcher::HandleResponse(const std::string& config_data,
+                                  int status,
+                                  int response_code) {}
+
+void HintsFetcher::OnURLLoadComplete(
+    std::unique_ptr<std::string> response_body) {}
+
+bool HintsFetcher::ParseGetHintsResponseAndApplyHints(
+    const optimization_guide::proto::GetHintsResponse& get_hints_response) {
+  ALLOW_UNUSED_LOCAL(hint_cache_);
+  return false;
+}
+
+}  // namespace previews

components/previews/content/hints_fetcher.h

@@ -0,0 +1,78 @@
+// Copyright 2019 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.
+
+#ifndef COMPONENTS_PREVIEWS_CONTENT_HINTS_FETCHER_H_
+#define COMPONENTS_PREVIEWS_CONTENT_HINTS_FETCHER_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/sequence_checker.h"
+#include "components/optimization_guide/proto/hints.pb.h"
+#include "components/previews/core/previews_experiments.h"
+#include "url/gurl.h"
+
+namespace previews {
+
+class HintCache;
+
+// A class to handle OnePlatform client requests for optimization hints from
+// the remote Optimization Guide Service.
+//
+// When Chrome starts up, if the client's OnePlatform hints have not been
+// updated in over day, this class will be triggered to fetch new hints from the
+// remote Optimization Guide Service. Owner must ensure that |hint_cache|
+// remains alive for the lifetime of |HintsFetcher|.
+class HintsFetcher {
+ public:
+  explicit HintsFetcher(HintCache* hint_cache);
+  ~HintsFetcher();
+
+  // Handles any configuration or checking needed and then
+  // initiates the fetch of OnePlatform Hints.
+  void FetchHintsForHosts(const std::vector<std::string>& hosts);
+
+ private:
+  // Creates the GetHintsResponse proto and executes the SimpleURLLoader request
+  // to the remote Optimization Guide Service with the |get_hints_request_|.
+  void GetRemoteHints(const std::vector<std::string>& hosts);
+
+  // Handles the response from the remote Optimization Guide Service.
+  // |response| is the response body, |status| is the
+  // |net::Error| of the response, and response_code is the HTTP
+  // response code (if available).
+  void HandleResponse(const std::string& response,
+                      int status,
+                      int response_code);
+
+  // URL loader completion callback.
+  void OnURLLoadComplete(std::unique_ptr<std::string> response_body);
+
+  // Parses the hints component of |get_hints_response| and applies it to
+  // |hints_|. Returns true if |get_hints_response| was successfully
+  // parsed and applied.
+  bool ParseGetHintsResponseAndApplyHints(
+      const optimization_guide::proto::GetHintsResponse& get_hints_response);
+
+  // Used to hold the GetHintsRequest being constructed and sent as a remote
+  // request.
+  std::unique_ptr<optimization_guide::proto::GetHintsRequest>
+      get_hints_request_;
+
+  // The URL for the remote Optimization Guide Service.
+  const GURL oneplatform_service_url_;
+
+  // The caller must ensure that the |hints_| outlives this instance.
+  HintCache* hint_cache_ = nullptr;
+
+  SEQUENCE_CHECKER(sequence_checker_);
+
+  DISALLOW_COPY_AND_ASSIGN(HintsFetcher);
+};
+
+}  // namespace previews
+
+#endif  // COMPONENTS_PREVIEWS_CONTENT_HINTS_FETCHER_H_

components/previews/content/previews_optimization_guide.cc

@@ -15,6 +15,7 @@
 #include "components/optimization_guide/optimization_guide_service.h"
 #include "components/optimization_guide/proto/hints.pb.h"
 #include "components/previews/content/hint_cache_leveldb_store.h"
+#include "components/previews/content/hints_fetcher.h"
 #include "components/previews/content/previews_hints.h"
 #include "components/previews/content/previews_hints_util.h"
 #include "components/previews/content/previews_top_host_provider.h"
@@ -226,6 +227,7 @@ void PreviewsOptimizationGuide::OnHintCacheInitialized() {
   // feature state:
   // (1) Data saver should be enabled
   // (2) Infobar notification does not need to be shown to the user.
+
   if (previews::params::IsOnePlatformHintsEnabled()) {
     // TODO(mcrouse): We will likely need to an async call and likely
     // within a timer that will call GetOnePlatformClientHints().
@@ -273,6 +275,12 @@ void PreviewsOptimizationGuide::GetOnePlatformClientHints() {
   LOCAL_HISTOGRAM_COUNTS_100("Previews.HintsFetcher.GetHintsRequest.HostCount",
                              top_hosts.size());
 
+  if (!hintsfetcher_) {
+    hintsfetcher_ = std::make_unique<HintsFetcher>(hint_cache_.get());
+  }
+
+  hintsfetcher_->FetchHintsForHosts(top_hosts);
+
   // TODO(mcrouse) to build SimpleURLLoader to perform request from service
   // for per-user client hints.
   // Pass callback for when URLLoader request is successful to call

components/previews/content/previews_optimization_guide.h

@@ -33,6 +33,7 @@ class Hint;
 
 namespace previews {
 
+class HintsFetcher;
 class PreviewsHints;
 class PreviewsTopHostProvider;
 class PreviewsUserData;
@@ -119,14 +120,13 @@ class PreviewsOptimizationGuide
                     const GURL& document_url,
                     const optimization_guide::proto::Hint* loaded_hint) const;
 
-  // Method to request OnePlatform client hints for user's sites with
-  // top engagement scores and creates a remote request to the OnePlatform
-  // Service. On request success OnOnePlatformHintsReceived callback will be
-  // called.
+  // Method to request OnePlatform client hints for user's sites with top
+  // engagement scores and creates a remote request using |hints_fetcher_| On
+  // request success OnOnePlatformHintsReceived callback will be called.
   void GetOnePlatformClientHints();
 
-  // Called when the response form the OnePlatform Service for hints is
-  // received.
+  // Called when the response from the OnePlatform Guide Service is handled and
+  // stored by the |hints_fetcher_|. received.
   void OnOnePlatformHintsReceived();
 
   // The OptimizationGuideService that this guide is listening to. Not owned.
@@ -150,8 +150,12 @@ class PreviewsOptimizationGuide
   // Used in testing to subscribe to an update event in this class.
   base::OnceClosure next_update_closure_;
 
+  // HintsFetcher handles the request to update Hints from OnePlatform Guide
+  // Service.
+  std::unique_ptr<HintsFetcher> hintsfetcher_;
+
   // TopHostProvider that this guide can query. Not owned.
-  PreviewsTopHostProvider* previews_top_host_provider_;
+  PreviewsTopHostProvider* previews_top_host_provider_ = nullptr;
 
   // Used to get |weak_ptr_| to self on the UI thread.
   base::WeakPtrFactory<PreviewsOptimizationGuide> ui_weak_ptr_factory_;