Avoid sending notifications when the bitmap data in history has not changed

chrome/browser/history/history_backend.cc

Index: chrome/browser/history/history_backend.cc
diff --git a/chrome/browser/history/history_backend.cc b/chrome/browser/history/history_backend.cc
index 34a0a30b2e08a7561fb6e5b7d50d8312fd1cab8d..e5a7c14bbf0b07d2a05f1a75e642d5344f2a1625 100644
--- a/chrome/browser/history/history_backend.cc
+++ b/chrome/browser/history/history_backend.cc
@@ -1931,6 +1931,13 @@ void HistoryBackend::MergeFavicon(
   bool replaced_bitmap = false;
   for (size_t i = 0; i < bitmap_id_sizes.size(); ++i) {
     if (bitmap_id_sizes[i].pixel_size == pixel_size) {
+      if (IsFaviconBitmapDataEqual(bitmap_id_sizes[i].bitmap_id, bitmap_data)) {
+        thumbnail_db_->SetFaviconBitmapLastUpdateTime(
+            bitmap_id_sizes[i].bitmap_id, base::Time::Now());
+        // Return early as merging did not alter the bitmap data.
+        ScheduleCommit();
+        return;
+      }
       thumbnail_db_->SetFaviconBitmap(bitmap_id_sizes[i].bitmap_id, bitmap_data,
           base::Time::Now());
       replaced_bitmap = true;
@@ -2316,6 +2323,20 @@ void HistoryBackend::SetFaviconSizes(FaviconID icon_id,
   thumbnail_db_->SetFaviconSizes(icon_id, favicon_sizes);
 }
 
+bool HistoryBackend::IsFaviconBitmapDataEqual(
+    FaviconBitmapID bitmap_id,
+    const scoped_refptr<base::RefCountedMemory>& new_bitmap_data) {
+  if (!new_bitmap_data.get())
+    return false;
+
+  scoped_refptr<base::RefCountedMemory> original_bitmap_data;
+  thumbnail_db_->GetFaviconBitmap(bitmap_id,
+                                  NULL,
+                                  &original_bitmap_data,
+                                  NULL);
+  return new_bitmap_data->Equals(original_bitmap_data);
+}
+
 bool HistoryBackend::GetFaviconsFromDB(
     const GURL& page_url,
     int icon_types,