Limit offline content suggestions to dino page

Previously, offline content suggestions would show on
any net error page. Now they only show on the dino page, as intended.
As a beneficial side-effect, the error strings (available on page load) will
indicate whether offline content may be inserted to the page later. This is
important for implementing the final UI because, for instance, we need to hide
error help suggestions to make room for content.

I moved the feature flag from browser/ to chrome/common so that it is accessible
from the error page code.

This code was previously reviewed here: https://chromium-review.googlesource.com/c/chromium/src/+/1185282
and needed move to another issue for an OOO reviewer.

Bug: 852872
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I86392d2b10d1f243525f043e0627b04f41f83b96
Reviewed-on: https://chromium-review.googlesource.com/1194245
Reviewed-by: Shakti Sahu <[email protected]>
Reviewed-by: Matt Menke <[email protected]>
Reviewed-by: Carlos Knippschild <[email protected]>
Reviewed-by: Peter Lee <[email protected]>
Commit-Queue: Dan H <[email protected]>
Cr-Commit-Position: refs/heads/master@{#586781}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 6c026bd..a35b486 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -144,7 +144,6 @@
 
 #if defined(OS_ANDROID)
 #include "chrome/browser/android/chrome_feature_list.h"
-#include "chrome/browser/android/download/new_net_error_page_feature.h"
 #include "chrome/browser/android/explore_sites/explore_sites_feature.h"
 #else  // OS_ANDROID
 #include "chrome/browser/media/router/media_router_feature.h"
@@ -1234,17 +1233,17 @@
 
 #if defined(OS_ANDROID)
 const FeatureEntry::FeatureParam kNewNetErrorPageUIContentList = {
-    chrome::android::new_net_error_ui::kUIAlternateParameterName,
-    chrome::android::new_net_error_ui::kUIAlternateContentList};
+    features::kNewNetErrorPageUIAlternateParameterName,
+    features::kNewNetErrorPageUIAlternateContentList};
 const FeatureEntry::FeatureParam kNewNetErrorPageUIContentListAutoDL = {
-    chrome::android::new_net_error_ui::kUIAlternateParameterName,
-    chrome::android::new_net_error_ui::kUIAlternateContentListAutoDownload};
+    features::kNewNetErrorPageUIAlternateParameterName,
+    features::kNewNetErrorPageUIAlternateContentListAutoDownload};
 const FeatureEntry::FeatureParam kNewNetErrorPageUIContentPreview = {
-    chrome::android::new_net_error_ui::kUIAlternateParameterName,
-    chrome::android::new_net_error_ui::kUIAlternateContentPreview};
+    features::kNewNetErrorPageUIAlternateParameterName,
+    features::kNewNetErrorPageUIAlternateContentPreview};
 const FeatureEntry::FeatureParam kNewNetErrorPageUIContentPreviewAutoDL = {
-    chrome::android::new_net_error_ui::kUIAlternateParameterName,
-    chrome::android::new_net_error_ui::kUIAlternateContentPreviewAutoDownload};
+    features::kNewNetErrorPageUIAlternateParameterName,
+    features::kNewNetErrorPageUIAlternateContentPreviewAutoDownload};
 
 const FeatureEntry::FeatureVariation kNewNetErrorPageUIVariations[] = {
     {"Content List", &kNewNetErrorPageUIContentList, 1, nullptr},
@@ -3699,7 +3698,7 @@
 #if defined(OS_ANDROID)
     {"new-net-error-page-ui", flag_descriptions::kNewNetErrorPageUIName,
      flag_descriptions::kNewNetErrorPageUIDescription, kOsAndroid,
-     FEATURE_WITH_PARAMS_VALUE_TYPE(chrome::android::kNewNetErrorPageUI,
+     FEATURE_WITH_PARAMS_VALUE_TYPE(features::kNewNetErrorPageUI,
                                     kNewNetErrorPageUIVariations,
                                     "NewNetErrorPageUI")},
 #endif  // defined(OS_ANDROID)