New tabCapture.captureOffscreenTab API, initially for Presentation API 1UA mode

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];
 
 class TabCaptureCaptureFunction : public ChromeSyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("tabCapture.capture", TABCAPTURE_CAPTURE)
 
- protected:
-  ~TabCaptureCaptureFunction() override {}
+ private:
+  ~TabCaptureCaptureFunction() final {}
 
   // ExtensionFunction:
-  bool RunSync() override;
+  bool RunSync() final;
 };
 
 class TabCaptureGetCapturedTabsFunction : public ChromeSyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("tabCapture.getCapturedTabs",
                              TABCAPTURE_GETCAPTUREDTABS)
 
- protected:
-  ~TabCaptureGetCapturedTabsFunction() override {}
+ private:
+  ~TabCaptureGetCapturedTabsFunction() final {}
 
   // ExtensionFunction:
-  bool RunSync() override;
+  bool RunSync() final;
+};
+
+class TabCaptureCaptureOffscreenTabFunction : public SyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("tabCapture.captureOffscreenTab",
+                             TABCAPTURE_CAPTUREOFFSCREENTAB)
+
+  // Examines the min/max width/height constraints in the |options| to determine
+  // a suitable initial off-screen tab size.
+  static gfx::Size DetermineInitialSize(
+      const extensions::api::tab_capture::CaptureOptions& options);
+
+ private:
+  ~TabCaptureCaptureOffscreenTabFunction() final {}
+
+  // ExtensionFunction:
+  bool RunSync() final;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_TAB_CAPTURE_TAB_CAPTURE_API_H_