chrome/blink: Add functionality for in-product help for media elements.

components/feature_engagement_tracker/public/feature_list.h

 // Copyright 2017 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_FEATURE_ENGAGEMENT_TRACKER_PUBLIC_FEATURE_LIST_H_
 #define COMPONENTS_FEATURE_ENGAGEMENT_TRACKER_PUBLIC_FEATURE_LIST_H_
 
 #include <vector>
 
 #include "base/feature_list.h"
 #include "build/build_config.h"
 #include "components/feature_engagement_tracker/public/feature_constants.h"
 #include "components/flags_ui/feature_entry.h"
 
 namespace feature_engagement_tracker {
 using FeatureVector = std::vector<const base::Feature*>;
 
 // The param name for the FeatureVariation configuration, which is used by
 // chrome://flags to set the variable name for the selected feature. The
 // FeatureEngagementTracker backend will then read this to figure out which
 // feature (if any) was selected by the end user.
 extern const char kIPHDemoModeFeatureChoiceParam[];
 
+// The command-line flag used to enable media download IPH feature in the
+// renderer.
+extern const char kEnableMediaDownloadIPH[];
+
 namespace {
 
 // Defines a const flags_ui::FeatureEntry::FeatureParam for the given
 // base::Feature. The constant name will be on the form
 // kFooFeature --> kFooFeatureVariation. The |feature_name| argument must
 // match the base::Feature::name member of the |base_feature|.
 // This is intended to be used with VARIATION_ENTRY below to be able to insert
 // it into an array of flags_ui::FeatureEntry::FeatureVariation.
 #define DEFINE_VARIATION_PARAM(base_feature, feature_name)                     \
   constexpr flags_ui::FeatureEntry::FeatureParam base_feature##Variation[] = { \
       {kIPHDemoModeFeatureChoiceParam, feature_name}}
 
 // Defines a single flags_ui::FeatureEntry::FeatureVariation entry, fully
 // enclosed. This is intended to be used with the declaration of
 // |kIPHDemoModeChoiceVariations| below.
 #define VARIATION_ENTRY(base_feature)                                \
   {                                                                  \
     base_feature##Variation[0].param_value, base_feature##Variation, \
         arraysize(base_feature##Variation), nullptr                  \
   }
 
 // Defines a flags_ui::FeatureEntry::FeatureParam for each feature.
 DEFINE_VARIATION_PARAM(kIPHDummyFeature, "IPH_Dummy");
 #if defined(OS_ANDROID)
 DEFINE_VARIATION_PARAM(kIPHDataSaverPreviewFeature, "IPH_DataSaverPreview");
 DEFINE_VARIATION_PARAM(kIPHDataSaverDetailFeature, "IPH_DataSaverDetail");
 DEFINE_VARIATION_PARAM(kIPHDownloadPageFeature, "IPH_DownloadPage");
 DEFINE_VARIATION_PARAM(kIPHDownloadHomeFeature, "IPH_DownloadHome");
+DEFINE_VARIATION_PARAM(kIPHMediaDownloadFeature, "IPH_MediaDownload");
 #endif  // OS_ANDROID
 
 }  // namespace
 
 // Defines the array of which features should be listed in the chrome://flags
 // UI to be able to select them alone for demo-mode. The features listed here
 // are possible to enable on their own in demo mode.
 constexpr flags_ui::FeatureEntry::FeatureVariation
     kIPHDemoModeChoiceVariations[] = {
 #if defined(OS_ANDROID)
         VARIATION_ENTRY(kIPHDataSaverPreviewFeature),
         VARIATION_ENTRY(kIPHDataSaverDetailFeature),
         VARIATION_ENTRY(kIPHDownloadPageFeature),
         VARIATION_ENTRY(kIPHDownloadHomeFeature),
+        VARIATION_ENTRY(kIPHMediaDownloadFeature),
 #else
         VARIATION_ENTRY(kIPHDummyFeature),  // Ensures non-empty array.
 #endif  // OS_ANDROID
 };
 
 #undef DEFINE_VARIATION_PARAM
 #undef VARIATION_ENTRY
 
 // Returns all the features that are in use for engagement tracking.
 FeatureVector GetAllFeatures();
 
 }  // namespace feature_engagement_tracker
 
 #endif  // COMPONENTS_FEATURE_ENGAGEMENT_TRACKER_PUBLIC_FEATURE_LIST_H_