Implementing URL prefix match for history thumbnail cache.

chrome/browser/history/top_sites_impl.cc

 // Copyright (c) 2013 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/history/top_sites_impl.h"
 
 #include <algorithm>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 273 matching lines @@
       return;
     }
     filtered_urls = thread_safe_cache_->top_sites();
   }
   callback.Run(filtered_urls);
 }
 
 bool TopSitesImpl::GetPageThumbnail(
     const GURL& url, scoped_refptr<base::RefCountedMemory>* bytes) {
   // WARNING: this may be invoked on any thread.
+  // Perform exact match.
   {
     base::AutoLock lock(lock_);
     if (thread_safe_cache_->GetPageThumbnail(url, bytes))
       return true;
   }
 
   // Resource bundle is thread safe.
   for (size_t i = 0; i < arraysize(kPrepopulatedPages); i++) {
     if (url == prepopulated_page_urls_[i]) {
       *bytes = ResourceBundle::GetSharedInstance().
           LoadDataResourceBytesForScale(
               kPrepopulatedPages[i].thumbnail_id,
               ui::SCALE_FACTOR_100P);
       return true;
     }
   }
 
+  // Still not found, so trim query, and perform prefix match.
+  {
+    GURL::Replacements replacements;
+    replacements.ClearQuery();
+    GURL url_no_query(url.ReplaceComponents(replacements));
+    base::AutoLock lock(lock_);
+    if (thread_safe_cache_->GetPageThumbnailForPrefix(url_no_query, bytes))
+      return true;
+  }
   return false;
 }
 
 bool TopSitesImpl::GetPageThumbnailScore(const GURL& url,
                                          ThumbnailScore* score) {
   // WARNING: this may be invoked on any thread.
   base::AutoLock lock(lock_);
   return thread_safe_cache_->GetPageThumbnailScore(url, score);
 }
 
@@ skipping 615 matching lines @@
   SetTopSites(pages);
 
   // Used only in testing.
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_TOP_SITES_UPDATED,
       content::Source<TopSitesImpl>(this),
       content::Details<CancelableRequestProvider::Handle>(&handle));
 }
 
 }  // namespace history