Add the partial screen magnifier to Chrome OS.

chrome/browser/chromeos/accessibility/accessibility_util.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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_ACCESSIBILITY_UTIL_H_
 #define CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_ACCESSIBILITY_UTIL_H_
 
 #include <string>
 
 namespace content {
 class WebUI;
 }
 
 namespace chromeos {
 namespace accessibility {
 
 // Enable or disable spoken feedback. Enabling spoken feedback installs the
 // ChromeVox component extension.  If this is being called in a login/oobe
 // login screen, pass the WebUI object in login_web_ui so that ChromeVox
 // can be injected directly into that screen, otherwise it should be NULL.
 void EnableSpokenFeedback(bool enabled, content::WebUI* login_web_ui);
 
 // Enable or disable the high contrast mode for Chrome.
 void EnableHighContrast(bool enabled);
 
-// Enable or disable the screen magnifier.
-void EnableScreenMagnifier(bool enabled);
+enum ScreenMagnifierType {
+  MagnifierNone,
+  MagnifierFull,
+  MagnifierPartial,
+};
+
+// Set the type of screen magnifier, or disable it.
+void SetScreenMagnifier(ScreenMagnifierType type);
 
 // Enable or disable the virtual keyboard.
 void EnableVirtualKeyboard(bool enabled);
 
 // Toggles whether Chrome OS spoken feedback is on or off. See docs for
 // EnableSpokenFeedback, above.
 void ToggleSpokenFeedback(content::WebUI* login_web_ui);
 
 // Speaks the specified string.
 void Speak(const std::string& utterance);
 
 // Returns true if spoken feedback is enabled, or false if not.
 bool IsSpokenFeedbackEnabled();
 
 // Returns true if High Contrast is enabled, or false if not.
 bool IsHighContrastEnabled();
 
-// Returns true if Screen Magnifier is enabled, or false if not.
-bool IsScreenMagnifierEnabled();
+// Returns the current state of the screen magnifier.
+ScreenMagnifierType GetScreenMagnifierType();
 
 // Speak the given text if the accessibility pref is already set.
 void MaybeSpeak(const std::string& utterance);
 
 }  // namespace accessibility
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_ACCESSIBILITY_UTIL_H_