NTP, Navi: Add whitelist for onboarding NTP backgrounds

This is to support being able to set a NTP background without requiring
a network call to load collections and album photos.

Bug: 924176
Change-Id: Ie19043170e144fbf03e4b7f9dbcffcf106a2107b
Reviewed-on: https://chromium-review.googlesource.com/c/1449103
Commit-Queue: John Lee <johntlee@chromium.org>
Reviewed-by: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628534}

chrome/browser/BUILD.gn

@@ -3008,6 +3008,8 @@ jumbo_split_static_library("browser") {
       "search/background/ntp_background_service_factory.cc",
       "search/background/ntp_background_service_factory.h",
       "search/background/ntp_background_service_observer.h",
+      "search/background/onboarding_ntp_backgrounds.cc",
+      "search/background/onboarding_ntp_backgrounds.h",
       "search/iframe_source.cc",
       "search/iframe_source.h",
       "search/instant_service.cc",

chrome/browser/search/background/ntp_background_service.cc

@@ -9,6 +9,7 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/net/system_network_context_manager.h"
 #include "chrome/browser/search/background/ntp_background.pb.h"
+#include "chrome/browser/search/background/onboarding_ntp_backgrounds.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/load_flags.h"
@@ -514,6 +515,12 @@ void NtpBackgroundService::RemoveObserver(
 }
 
 bool NtpBackgroundService::IsValidBackdropUrl(const GURL& url) const {
+  for (auto& onboarding_background : GetOnboardingNtpBackgrounds()) {
+    if (onboarding_background == url) {
+      return true;
+    }
+  }
+
   for (auto& image : collection_images_) {
     if (image.image_url == url)
       return true;

chrome/browser/search/background/onboarding_ntp_backgrounds.cc

+// 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 "chrome/browser/search/background/onboarding_ntp_backgrounds.h"
+
+#include "url/gurl.h"
+
+std::array<GURL, kOnboardingNtpBackgroundsCount> GetOnboardingNtpBackgrounds() {
+  // A set of whitelisted NTP background image URLs that are always considered
+  // to be valid URLs that are shown to the user as part of the Onboarding flow.
+  // These backgrounds were handpicked from the Backdrop API.
+  const std::array<GURL, kOnboardingNtpBackgroundsCount>
+      kOnboardingNtpBackgrounds = {
+          {// Art
+           GURL(
+               "https://lh4.googleusercontent.com/proxy/"
+               "rh9ut9biDoATqaadvgilbUAkIDo50op0G9056C1TnbfK5063_"
+               "M1OzTyOSfgbHbwcXzWz-UoM19yeObH2gXCX8wB8hVPbc_MXHBMfJWUmpg1Tg0s="
+               "w3840-h2160-p-k-no-nd-mv"),
+
+           // Landscape
+           GURL("https://lh6.googleusercontent.com/proxy/"
+                "5YUVHiA1x4KXBMvcnQ_"
+                "fNcsGFQig9vpKgEbH98vc3mIx6963Jawv4WtVMemvIEdCHGpo60iD8t0OfwnHu"
+                "5w"
+                "Y5InXTyqTPZx4a77T7iIFnHti=w3840-h2160-p-k-no-nd-mv"),
+
+           // Cityscape
+           GURL(
+               "https://lh6.googleusercontent.com/proxy/"
+               "Ym39mP3aRahUqQD_W1bks3MdDZx-Mea7_ajAs293LciDm70mFzpsswh_"
+               "QBJVFeUMWYF2jIQFvcBPeEdNAAwBlFNc2PsINAWHXe68Kg=w3840-h2160-p-k-"
+               "no-nd-mv"),
+
+           // Seascape
+           GURL("https://lh4.googleusercontent.com/proxy/"
+                "hl6qyPDq9FBOuU8G1A3X2khJJdAzfccHtIoX7hHtlkR4tgj_"
+                "WJvpj4s8FX8cb8u9R6xhrp96xXJIIFrTK8Rdpqh0tTiSfL5k_OXcWw=w3840-"
+                "h2160-p-k-no-nd-mv"),
+
+           // Geometric forms
+           GURL("https://lh5.googleusercontent.com/proxy/"
+                "Dm41Zdz8s5TnQcIRSCnAXUvHItsB67S7U3DytjCwsIpG9SmJKsVkkBRCK0ODme"
+                "vy"
+                "_M47-2CSAxGzFaiJM3bHaPfVT90Fm6lBbNd2yueqMg=w3840-h2160-p-k-no-"
+                "nd-mv")}};
+  return kOnboardingNtpBackgrounds;
+}

chrome/browser/search/background/onboarding_ntp_backgrounds.h

+// 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 CHROME_BROWSER_SEARCH_BACKGROUND_ONBOARDING_NTP_BACKGROUNDS_H_
+#define CHROME_BROWSER_SEARCH_BACKGROUND_ONBOARDING_NTP_BACKGROUNDS_H_
+
+#include <array>
+
+#include "url/gurl.h"
+
+const size_t kOnboardingNtpBackgroundsCount = 5;
+std::array<GURL, kOnboardingNtpBackgroundsCount> GetOnboardingNtpBackgrounds();
+
+#endif  // CHROME_BROWSER_SEARCH_BACKGROUND_ONBOARDING_NTP_BACKGROUNDS_H_