favicons: adds GetFaviconsLastUpdatedBefore()

To FaviconDatabase. I'm going to use this in weblayer code
to expire favicons. WebLayer doesn't use history, but needs
a way to prune the database.

BUG=1076463
TEST=covered by tests

Change-Id: If74a389a947eb465447009c620e0988f9545ab91
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354998
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798209}

components/favicon/core/favicon_database.cc

@@ -843,6 +843,23 @@ bool FaviconDatabase::HasMappingFor(favicon_base::FaviconID id) {
   return statement.Step();
 }
 
+std::vector<favicon_base::FaviconID>
+FaviconDatabase::GetFaviconsLastUpdatedBefore(base::Time time, int max_count) {
+  sql::Statement statement(db_.GetCachedStatement(SQL_FROM_HERE,
+                                                  "SELECT icon_id "
+                                                  "FROM favicon_bitmaps "
+                                                  "WHERE last_updated < ? "
+                                                  "ORDER BY last_updated ASC "
+                                                  "LIMIT ?"));
+  statement.BindInt64(0, time.ToDeltaSinceWindowsEpoch().InMicroseconds());
+  statement.BindInt64(
+      1, max_count == 0 ? std::numeric_limits<int64_t>::max() : max_count);
+  std::vector<favicon_base::FaviconID> ids;
+  while (statement.Step())
+    ids.push_back(statement.ColumnInt64(0));
+  return ids;
+}
+
 bool FaviconDatabase::InitIconMappingEnumerator(
     favicon_base::IconType type,
     IconMappingEnumerator* enumerator) {

components/favicon/core/favicon_database.h

@@ -222,6 +222,12 @@ class FaviconDatabase {
   // Checks whether a favicon is used by any URLs in the database.
   bool HasMappingFor(favicon_base::FaviconID id);
 
+  // Returns the ids of favicons which were last updated before |time|. This
+  // returns at most |max_count| ids.
+  std::vector<favicon_base::FaviconID> GetFaviconsLastUpdatedBefore(
+      base::Time time,
+      int max_count);
+
   // The class to enumerate icon mappings. Use InitIconMappingEnumerator to
   // initialize.
   class IconMappingEnumerator {

components/favicon/core/favicon_database_unittest.cc

@@ -1376,4 +1376,54 @@ TEST(FaviconDatabaseIconTypeTest, ShouldBeBackwardCompatible) {
             FaviconDatabase::FromPersistedIconType(16));
 }
 
+TEST_F(FaviconDatabaseTest, GetFaviconsLastUpdatedBefore) {
+  FaviconDatabase db;
+  ASSERT_EQ(sql::INIT_OK, db.Init(file_name_));
+  db.BeginTransaction();
+
+  std::vector<unsigned char> data(kBlob1, kBlob1 + sizeof(kBlob1));
+  scoped_refptr<base::RefCountedBytes> favicon(new base::RefCountedBytes(data));
+
+  // Add two favicons, 10 seconds apart. |time1| is after |time2|.
+  GURL url("http://google.com");
+  const base::Time time1 = base::Time::Now();
+  favicon_base::FaviconID id1 =
+      db.AddFavicon(url, favicon_base::IconType::kTouchIcon, favicon,
+                    FaviconBitmapType::ON_VISIT, time1, gfx::Size());
+  EXPECT_NE(0u, id1);
+
+  const base::Time time2 = time1 - base::TimeDelta::FromSeconds(10);
+  favicon_base::FaviconID id2 =
+      db.AddFavicon(url, favicon_base::IconType::kTouchIcon, favicon,
+                    FaviconBitmapType::ON_VISIT, time2, gfx::Size());
+  EXPECT_NE(0u, id2);
+  EXPECT_NE(id1, id2);
+
+  // There should be no favicons before |time2|.
+  EXPECT_TRUE(db.GetFaviconsLastUpdatedBefore(
+                    time2 - base::TimeDelta::FromSeconds(1), 10)
+                  .empty());
+
+  // Requesting a time after |time2| should return |id2|.
+  auto ids = db.GetFaviconsLastUpdatedBefore(
+      time2 + base::TimeDelta::FromSeconds(1), 10);
+  ASSERT_EQ(1u, ids.size());
+  EXPECT_EQ(id2, ids[0]);
+
+  // There should two favicons when using a time after |time1|.
+  ids = db.GetFaviconsLastUpdatedBefore(time1 + base::TimeDelta::FromSeconds(1),
+                                        10);
+  ASSERT_EQ(2u, ids.size());
+  // |id2| is before |id1|, so it should be returned first.
+  EXPECT_EQ(id2, ids[0]);
+  EXPECT_EQ(id1, ids[1]);
+
+  // Repeat previous, but cap the max at 1.
+  ids = db.GetFaviconsLastUpdatedBefore(time1 + base::TimeDelta::FromSeconds(1),
+                                        1);
+  ASSERT_EQ(1u, ids.size());
+  // |id2| is before |id1|, so it should be returned first.
+  EXPECT_EQ(id2, ids[0]);
+}
+
 }  // namespace favicon

components/favicon_base/favicon_types.h

@@ -19,7 +19,7 @@ namespace favicon_base {
 
 struct FallbackIconStyle;
 
-typedef int64_t FaviconID;
+using FaviconID = int64_t;
 
 // Defines the icon types.
 //
@@ -95,7 +95,7 @@ struct FaviconRawBitmapResult {
 
 // Define type with same structure as FaviconRawBitmapResult for passing data to
 // HistoryBackend::SetFavicons().
-typedef FaviconRawBitmapResult FaviconRawBitmapData;
+using FaviconRawBitmapData = FaviconRawBitmapResult;
 
 // Result returned by LargeIconService::GetLargeIconOrFallbackStyle(). Contains
 // either the bitmap data if the favicon database has a sufficiently large