Add favicon database histograms to UMA.

components/history/core/browser/thumbnail_database.cc

Index: components/history/core/browser/thumbnail_database.cc
diff --git a/components/history/core/browser/thumbnail_database.cc b/components/history/core/browser/thumbnail_database.cc
index 05a247dc4929d1460821356f19cd9d00a3b8ec87..cd88640029659cf7491a03a8aaed315ca9dca349 100644
--- a/components/history/core/browser/thumbnail_database.cc
+++ b/components/history/core/browser/thumbnail_database.cc
@@ -613,11 +613,67 @@ sql::InitStatus ThumbnailDatabase::Init(const base::FilePath& db_name) {
 }
 
 void ThumbnailDatabase::ComputeDatabaseMetrics() {
-  sql::Statement favicon_count(
-      db_.GetCachedStatement(SQL_FROM_HERE, "SELECT COUNT(*) FROM favicons"));
-  UMA_HISTOGRAM_COUNTS_10000(
-      "History.NumFaviconsInDB",
-      favicon_count.Step() ? favicon_count.ColumnInt(0) : 0);
+  base::TimeTicks start_time = base::TimeTicks::Now();
+
+  // Calculate the size of the favicon database.
+  {
+    sql::Statement page_count(
+        db_.GetCachedStatement(SQL_FROM_HERE, "PRAGMA page_count"));
+    int64 page_count_bytes = page_count.Step() ? page_count.ColumnInt64(0) : 0;
+    sql::Statement page_size(
+        db_.GetCachedStatement(SQL_FROM_HERE, "PRAGMA page_size"));
+    int64 page_size_bytes = page_size.Step() ? page_size.ColumnInt64(0) : 0;
+    int file_mb = static_cast<int>(
+      (page_count_bytes * page_size_bytes) / (1024 * 1024));
+    UMA_HISTOGRAM_MEMORY_MB("History.FaviconDatabaseSizeMB", file_mb);

[Roger McFarlane (Chromium), 2015/03/25 18:20:18]

KB?

[beaudoin, 2015/03/25 18:31:48]

+1, MB has an overly large first bin.

+  }
+
+  // Count all icon files referenced by the DB.
+  {
+    sql::Statement favicon_count(
+        db_.GetCachedStatement(SQL_FROM_HERE, "SELECT COUNT(*) FROM favicons"));
+    UMA_HISTOGRAM_COUNTS_10000(
+        "History.NumFaviconsInDB",
+        favicon_count.Step() ? favicon_count.ColumnInt(0) : 0);
+  }
+
+  // Count all bitmap resources cached in the DB.
+  {
+    sql::Statement bitmap_count(
+        db_.GetCachedStatement(
+            SQL_FROM_HERE, "SELECT COUNT(*) FROM favicon_bitmaps"));
+    UMA_HISTOGRAM_COUNTS_10000(
+        "History.NumFaviconBitmapsInDB",
+        bitmap_count.Step() ? bitmap_count.ColumnInt(0) : 0);
+  }
+
+  // Count the subset of "large" icon files referenced by the DB.
+  {
+    sql::Statement large_favicon_count(
+        db_.GetCachedStatement(
+            SQL_FROM_HERE,
+            "SELECT COUNT(*) FROM favicons WHERE icon_type > ?"));

[beaudoin, 2015/03/25 18:31:48]

I think I'd prefer something like "width > 64" or "width > 128" (whichever is
our current cutoff) since we may eventually decide to keep large favicons using
favicon_base::FAVICON.

[brettw, 2015/03/25 19:38:53]

Also, I think this allows you to delete the large bitmap check below. The nested
select will have much worse performance, so we should only do that if it's
really necessary, and it doesn't seem so.

[Roger McFarlane (Chromium), 2015/03/26 18:26:33]

The schema doesn't quite allow for this, but perhaps simply counting the large
bitmaps is sufficient.

I.e., we can't directly (without join) count the number of icons urls which map
to stored large icon bitmaps. Icons (more precicely icon urls) are stored with a
type, but only bitmaps are stored with size (since a given icon file can map to
multiple bitmaps).

This histogram counts the number of candidate urls at which we expect to find
large icons.

+    large_favicon_count.BindInt64(0, favicon_base::FAVICON);
+    UMA_HISTOGRAM_COUNTS_10000(
+        "History.NumLargeFaviconsInDB",
+        large_favicon_count.Step() ? large_favicon_count.ColumnInt(0) : 0);
+  }
+
+  // Count the subset of "large" bitmap resources cached in the DB.
+  {
+    sql::Statement large_bitmap_count(
+        db_.GetCachedStatement(
+            SQL_FROM_HERE,
+            "SELECT COUNT(*) FROM favicon_bitmaps "
+            "WHERE id IN (SELECT id FROM favicons WHERE icon_type > ?)"));
+    large_bitmap_count.BindInt64(0, favicon_base::FAVICON);
+    UMA_HISTOGRAM_COUNTS_10000(
+        "History.NumLargeFaviconBitmapsInDB",
+        large_bitmap_count.Step() ? large_bitmap_count.ColumnInt(0) : 0);
+  }
+
+  UMA_HISTOGRAM_TIMES("History.FaviconDatabaseAdvancedMetricsTime",
+                      base::TimeTicks::Now() - start_time);
 }
 
 void ThumbnailDatabase::BeginTransaction() {