cefclient: Move StringResourceMap to ClientHandler (see issue #2586)

Fixes a DCHECK when creating multiple windows in cefclient due to the creation
of multiple StringResourceProvider objects.

tests/cefclient/browser/client_handler.h

@@ -14,6 +14,7 @@
 #include "include/wrapper/cef_message_router.h"
 #include "include/wrapper/cef_resource_manager.h"
 #include "tests/cefclient/browser/client_types.h"
+#include "tests/cefclient/browser/test_runner.h"
 
 #if defined(OS_LINUX)
 #include "tests/cefclient/browser/dialog_handler_gtk.h"
@@ -293,6 +294,9 @@ class ClientHandler : public CefClient,
   // Show SSL information for the current site.
   void ShowSSLInformation(CefRefPtr<CefBrowser> browser);
 
+  // Set a string resource for loading via StringResourceProvider.
+  void SetStringResource(const std::string& page, const std::string& data);
+
   // Returns the Delegate.
   Delegate* delegate() const { return delegate_; }
 
@@ -367,6 +371,10 @@ class ClientHandler : public CefClient,
   // Manages the registration and delivery of resources.
   CefRefPtr<CefResourceManager> resource_manager_;
 
+  // Used to manage string resources in combination with StringResourceProvider.
+  // Only accessed on the IO thread.
+  test_runner::StringResourceMap string_resource_map_;
+
   // MAIN THREAD MEMBERS
   // The following members will only be accessed on the main thread. This will
   // be the same as the CEF UI thread except when using multi-threaded message