Support PNG and quality control in chrome.tabs.captureVisibleTab().

chrome/browser/extensions/extension_function.h

Index: chrome/browser/extensions/extension_function.h
diff --git a/chrome/browser/extensions/extension_function.h b/chrome/browser/extensions/extension_function.h
index 272d6c1695c2587a105645cf02ec6e9d8da6d596..1727ae08adc3ad146b6e13dec324ac690122ea04 100644
--- a/chrome/browser/extensions/extension_function.h
+++ b/chrome/browser/extensions/extension_function.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
@@ -176,6 +176,8 @@ class AsyncExtensionFunction : public ExtensionFunction {
     return static_cast<DictionaryValue*>(args_.get());
   }
 
+  bool HasOptionalArgument(size_t index);
+
   // Note: After Run() returns, dispatcher() can be NULL.  Since these getters
   // rely on dispatcher(), make sure it is valid before using them.
   std::string extension_id();