Implementing URL prefix match for history thumbnail cache.

chrome/browser/history/top_sites_impl.cc

Index: chrome/browser/history/top_sites_impl.cc
diff --git a/chrome/browser/history/top_sites_impl.cc b/chrome/browser/history/top_sites_impl.cc
index c8f04660663ed1d5af5023a1a69a25c9d0876523..c874f1f55fa98a9c039b2b9b41d80358a9073b8b 100644
--- a/chrome/browser/history/top_sites_impl.cc
+++ b/chrome/browser/history/top_sites_impl.cc
@@ -291,6 +291,7 @@ void TopSitesImpl::GetMostVisitedURLs(
 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))
@@ -308,6 +309,15 @@ bool TopSitesImpl::GetPageThumbnail(
     }
   }
 
+  // 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;
 }