[DevTools] Create last agents on attach, modify InspectorDatabaseAgent to support it.

third_party/WebKit/Source/modules/webdatabase/DatabaseTracker.h

Index: third_party/WebKit/Source/modules/webdatabase/DatabaseTracker.h
diff --git a/third_party/WebKit/Source/modules/webdatabase/DatabaseTracker.h b/third_party/WebKit/Source/modules/webdatabase/DatabaseTracker.h
index 9b6059eede6a8d8f4f4cd51cbe28d22c36f63d2d..93b3f2fdd52b8677619d6e7f2bf9542b5c1c84d7 100644
--- a/third_party/WebKit/Source/modules/webdatabase/DatabaseTracker.h
+++ b/third_party/WebKit/Source/modules/webdatabase/DatabaseTracker.h
@@ -32,6 +32,7 @@
 #include "modules/ModulesExport.h"
 #include "modules/webdatabase/DatabaseError.h"
 #include "platform/heap/Handle.h"
+#include "wtf/Functional.h"
 #include "wtf/HashMap.h"
 #include "wtf/HashSet.h"
 #include "wtf/ThreadingPrimitives.h"
@@ -42,6 +43,7 @@ namespace blink {
 
 class Database;
 class DatabaseContext;
+class Page;
 class SecurityOrigin;
 
 class MODULES_EXPORT DatabaseTracker {
@@ -65,6 +67,9 @@ public:
 
     void closeDatabasesImmediately(SecurityOrigin*, const String& name);
 
+    using DatabaseCallback = Function<void(Database*)>;
+    void forEachOpenDatabaseInPage(Page*, PassOwnPtr<DatabaseCallback>);
+
     void prepareToOpenDatabase(Database*);
     void failedToOpenDatabase(Database*);