Replace the usage of SkBitmap with gfx::Image in the suggestion service.

chrome/browser/android/ntp/most_visited_sites.cc

Index: chrome/browser/android/ntp/most_visited_sites.cc
diff --git a/components/ntp_tiles/most_visited_sites.cc b/chrome/browser/android/ntp/most_visited_sites.cc
similarity index 93%
copy from components/ntp_tiles/most_visited_sites.cc
copy to chrome/browser/android/ntp/most_visited_sites.cc
index 4396851b671f055f47d1c05808daeb6a5a511a51..2cff04d7dfaa9b34c5269bf1f7ec8e3f54d0c804 100644
--- a/components/ntp_tiles/most_visited_sites.cc
+++ b/chrome/browser/android/ntp/most_visited_sites.cc
@@ -2,10 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "components/ntp_tiles/most_visited_sites.h"
+#include "chrome/browser/android/ntp/most_visited_sites.h"
 
-#include <algorithm>
-#include <set>
 #include <utility>
 
 #include "base/callback.h"
@@ -24,10 +22,12 @@
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_service.h"
 #include "components/variations/variations_associated_data.h"
+#include "content/public/browser/browser_thread.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/codec/jpeg_codec.h"
 #include "url/gurl.h"
 
+using content::BrowserThread;
 using history::TopSites;
 using suggestions::ChromeSuggestion;
 using suggestions::SuggestionsProfile;
@@ -63,13 +63,13 @@ enum MostVisitedTileType {
     NUM_TILE_TYPES,
 };
 
-// May only be called from blocking thread pool.
-std::unique_ptr<SkBitmap> TryFetchLocalThumbnail(
+std::unique_ptr<SkBitmap> MaybeFetchLocalThumbnail(
     const GURL& url,
     const scoped_refptr<TopSites>& top_sites) {
+  DCHECK_CURRENTLY_ON(BrowserThread::DB);
   scoped_refptr<base::RefCountedMemory> image;
   std::unique_ptr<SkBitmap> bitmap;
-  if (top_sites->GetPageThumbnail(url, false, &image))
+  if (top_sites && top_sites->GetPageThumbnail(url, false, &image))
     bitmap = gfx::JPEGCodec::Decode(image->front(), image->size());
   return bitmap;
 }
@@ -169,7 +169,6 @@ MostVisitedSites::Suggestion&
 MostVisitedSites::Suggestion::operator=(Suggestion&&) = default;
 
 MostVisitedSites::MostVisitedSites(
-    scoped_refptr<base::SequencedWorkerPool> blocking_pool,
     PrefService* prefs,
     const TemplateURLService* template_url_service,
     variations::VariationsService* variations_service,
@@ -193,12 +192,7 @@ MostVisitedSites::MostVisitedSites(
       recorded_uma_(false),
       scoped_observer_(this),
       mv_source_(SUGGESTIONS_SERVICE),
-      blocking_pool_(std::move(blocking_pool)),
-      blocking_runner_(blocking_pool_->GetTaskRunnerWithShutdownBehavior(
-          base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN)),
       weak_ptr_factory_(this) {
-  DCHECK(top_sites_);
-  DCHECK(suggestions_service_);
   supervisor_->SetObserver(this);
 }
 
@@ -215,8 +209,8 @@ void MostVisitedSites::SetMostVisitedURLsObserver(Observer* observer,
   if (ShouldShowPopularSites() &&
       NeedPopularSites(prefs_, num_sites_)) {
     popular_sites_.reset(new PopularSites(
-        blocking_pool_, prefs_, template_url_service_, variations_service_,
-        download_context_, popular_sites_directory_, GetPopularSitesCountry(),
+        prefs_, template_url_service_, variations_service_, download_context_,
+        popular_sites_directory_, GetPopularSitesCountry(),
         GetPopularSitesVersion(), false,
         base::Bind(&MostVisitedSites::OnPopularSitesAvailable,
                    base::Unretained(this))));
@@ -224,13 +218,16 @@ void MostVisitedSites::SetMostVisitedURLsObserver(Observer* observer,
     received_popular_sites_ = true;
   }
 
-  // TopSites updates itself after a delay. To ensure up-to-date results,
-  // force an update now.
-  top_sites_->SyncWithHistory();
+  // TODO(treib): Can |top_sites_| ever be null? If not, remove these checks.
+  if (top_sites_) {
+    // TopSites updates itself after a delay. To ensure up-to-date results,
+    // force an update now.
+    top_sites_->SyncWithHistory();
 
-  // Register as TopSitesObserver so that we can update ourselves when the
-  // TopSites changes.
-  scoped_observer_.Add(top_sites_.get());
+    // Register as TopSitesObserver so that we can update ourselves when the
+    // TopSites changes.
+    scoped_observer_.Add(top_sites_.get());
+  }
 
   suggestions_subscription_ = suggestions_service_->AddCallback(
       base::Bind(&MostVisitedSites::OnSuggestionsProfileAvailable,
@@ -245,11 +242,12 @@ void MostVisitedSites::SetMostVisitedURLsObserver(Observer* observer,
 
 void MostVisitedSites::GetURLThumbnail(const GURL& url,
                                        const ThumbnailCallback& callback) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  base::PostTaskAndReplyWithResult(
-      blocking_runner_.get(), FROM_HERE,
-      base::Bind(&TryFetchLocalThumbnail, url, top_sites_),
+  // TODO(treib): Move this to the blocking pool? Doesn't seem related to DB.
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::DB, FROM_HERE,
+      base::Bind(&MaybeFetchLocalThumbnail, url, top_sites_),
       base::Bind(&MostVisitedSites::OnLocalThumbnailFetched,
                  weak_ptr_factory_.GetWeakPtr(), url, callback));
 }
@@ -258,7 +256,7 @@ void MostVisitedSites::OnLocalThumbnailFetched(
     const GURL& url,
     const ThumbnailCallback& callback,
     std::unique_ptr<SkBitmap> bitmap) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
   if (bitmap.get()) {
     callback.Run(true /* is_local_thumbnail */, bitmap.get());
     return;
@@ -266,7 +264,8 @@ void MostVisitedSites::OnLocalThumbnailFetched(
 
   // A thumbnail is not locally available for |url|. Make sure it is put in
   // the list to be fetched at the next visit to this site.
-  top_sites_->AddForcedURL(url, base::Time::Now());
+  if (top_sites_)
+    top_sites_->AddForcedURL(url, base::Time::Now());
   // Also fetch a remote thumbnail if possible. PopularSites or the
   // SuggestionsService can supply a thumbnail download URL.
   if (popular_sites_) {
@@ -295,7 +294,7 @@ void MostVisitedSites::OnObtainedThumbnail(bool is_local_thumbnail,
                                            const ThumbnailCallback& callback,
                                            const GURL& url,
                                            const gfx::Image& image) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
   const SkBitmap* bitmap = nullptr;
   if (!image.IsEmpty())
     bitmap = image.ToSkBitmap();
@@ -305,10 +304,12 @@ void MostVisitedSites::OnObtainedThumbnail(bool is_local_thumbnail,
 void MostVisitedSites::AddOrRemoveBlacklistedUrl(const GURL& url,
                                                  bool add_url) {
   // Always blacklist in the local TopSites.
-  if (add_url)
-    top_sites_->AddBlacklistedURL(url);
-  else
-    top_sites_->RemoveBlacklistedURL(url);
+  if (top_sites_) {
+    if (add_url)
+      top_sites_->AddBlacklistedURL(url);
+    else
+      top_sites_->RemoveBlacklistedURL(url);
+  }
 
   // Only blacklist in the server-side suggestions service if it's active.
   if (mv_source_ == SUGGESTIONS_SERVICE) {
@@ -378,6 +379,9 @@ void MostVisitedSites::BuildCurrentSuggestions() {
 }
 
 void MostVisitedSites::InitiateTopSitesQuery() {
+  if (!top_sites_)
+    return;
+
   top_sites_->GetMostVisitedURLs(
       base::Bind(&MostVisitedSites::OnMostVisitedURLsAvailable,
                  weak_ptr_factory_.GetWeakPtr()),
@@ -471,7 +475,7 @@ MostVisitedSites::CreateWhitelistEntryPointSuggestions(
 
   for (const auto& whitelist : supervisor_->whitelists()) {
     // Skip blacklisted sites.
-    if (top_sites_->IsBlacklisted(whitelist.entry_point))
+    if (top_sites_ && top_sites_->IsBlacklisted(whitelist.entry_point))
       continue;
 
     // Skip suggestions already present.
@@ -522,7 +526,7 @@ MostVisitedSites::CreatePopularSitesSuggestions(
       hosts.insert(suggestion->url.host());
     for (const PopularSites::Site& popular_site : popular_sites_->sites()) {
       // Skip blacklisted sites.
-      if (top_sites_->IsBlacklisted(popular_site.url))
+      if (top_sites_ && top_sites_->IsBlacklisted(popular_site.url))
         continue;
       std::string host = popular_site.url.host();
       // Skip suggestions already present in personal or whitelists.