Move more code from headers to implementation.

chrome/browser/history/history_types.cc

Index: chrome/browser/history/history_types.cc
diff --git a/chrome/browser/history/history_types.cc b/chrome/browser/history/history_types.cc
index eebe5a7853f139714a38ce860a4ed5323d2d93c0..8a41ae81201904e7b156ae59746ee0dc102cac3a 100644
--- a/chrome/browser/history/history_types.cc
+++ b/chrome/browser/history/history_types.cc
@@ -335,6 +335,12 @@ Images::Images() {}
 
 Images::~Images() {}
 
+// TopSitesDelta --------------------------------------------------------------
+
+TopSitesDelta::TopSitesDelta() {}
+
+TopSitesDelta::~TopSitesDelta() {}
+
 // HistoryAddPageArgs ---------------------------------------------------------
 
 HistoryAddPageArgs::HistoryAddPageArgs(
@@ -366,7 +372,12 @@ HistoryAddPageArgs* HistoryAddPageArgs::Clone() const {
       visit_source, did_replace_entry);
 }
 
-MostVisitedThumbnails::MostVisitedThumbnails() {
-}
+ThumbnailMigration::ThumbnailMigration() {}
+
+ThumbnailMigration::~ThumbnailMigration() {}
+
+MostVisitedThumbnails::MostVisitedThumbnails() {}
+
+MostVisitedThumbnails::~MostVisitedThumbnails() {}
 
 }  // namespace history