unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, CefVcl, CefLib;

type
  TMyRenderProcessHandler = class(TCefRenderProcessHandlerOwn)
  protected
    function OnBeforeNavigation(const browser: ICefBrowser;
      const frame: ICefFrame; const request: ICefRequest;
      navigationType: TCefNavigationType; isRedirect: Boolean): Boolean;
      override;
  end;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    FChromium: TChromium;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  MiddleDown: Boolean;

implementation

{$R *.dfm}

function MouseProc(nCode: Integer; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
var
  HookStruct: TMouseHookStruct;
begin
  HookStruct := PMouseHookStruct(lParam)^;

  if (nCode >= 0) then
  begin
    case wParam of
      WM_MBUTTONDOWN: MiddleDown := True;
      WM_LBUTTONDOWN, WM_RBUTTONDOWN: MiddleDown := False;
    end;
  end;

  Result := CallNextHookEx(0, nCode, wParam, lParam);
end;

procedure TForm1.FormCreate(Sender: TObject);
var
  ThreadID: DWORD;
begin
  FChromium := TChromium.Create(Self);
  FChromium.Parent := Self;
  FChromium.SetBounds(8, 8, 500, 500);
  FChromium.Load('http://www.google.com');

  ThreadID := GetWindowThreadProcessId(FChromium.Browser.Host.WindowHandle, nil);
  SetWindowsHookEx(WH_MOUSE, MouseProc, 0, ThreadID);
end;

{ TMyRenderProcessHandler }

function TMyRenderProcessHandler.OnBeforeNavigation(
  const browser: ICefBrowser; const frame: ICefFrame;
  const request: ICefRequest; navigationType: TCefNavigationType;
  isRedirect: Boolean): Boolean;
begin
  Result := False;

  if MiddleDown and (navigationType = NAVIGATION_LINK_CLICKED) then
  begin
    Result := True;
    ShowMessage('Link was clicked by a middle mouse button!');
  end;
end;

initialization
  CefRenderProcessHandler := TMyRenderProcessHandler.Create;

end.