Add a fake cast extension for testing.

chrome/browser/extensions/api/tab_capture/tab_capture_api.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Defines the Chrome Extensions Tab Capture API functions for accessing
 // tab media streams.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_TAB_CAPTURE_TAB_CAPTURE_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_TAB_CAPTURE_TAB_CAPTURE_API_H_
 
 #include "chrome/browser/extensions/api/tab_capture/tab_capture_registry.h"
 #include "chrome/browser/extensions/chrome_extension_function.h"
 #include "chrome/common/extensions/api/tab_capture.h"
 
 namespace extensions {
 
 // Extension ids for the chromecast.
-extern const char* const kChromecastExtensionIds[6];
+extern const char* const kChromecastExtensionIds[7];
 
 class TabCaptureCaptureFunction : public ChromeSyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("tabCapture.capture", TABCAPTURE_CAPTURE)
 
  protected:
   ~TabCaptureCaptureFunction() override {}
 
   // ExtensionFunction:
   bool RunSync() override;
 };
 
 class TabCaptureGetCapturedTabsFunction : public ChromeSyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("tabCapture.getCapturedTabs",
                              TABCAPTURE_GETCAPTUREDTABS)
 
  protected:
   ~TabCaptureGetCapturedTabsFunction() override {}
 
   // ExtensionFunction:
   bool RunSync() override;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_TAB_CAPTURE_TAB_CAPTURE_API_H_