Add the partial screen magnifier to Chrome OS.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 1c499a5b79d638833947f401d122c7a1bcf00f45..2fbb6c01de06fa74a54761212f8124185ce94256 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -14342,9 +14342,18 @@ Press any key to continue exploring.
       <message name="IDS_OPTIONS_SETTINGS_ACCESSIBILITY_HIGH_CONTRAST_DESCRIPTION" desc="In the settings tab, the text next to the checkbox for high contrast mode.">
         Enable high contrast mode
       </message>
-      <message name="IDS_OPTIONS_SETTINGS_ACCESSIBILITY_SCREEN_MAGNIFIER_DESCRIPTION" desc="In the settings tab, the text next to the checkbox for screen magnifier.">
+      <message name="IDS_OPTIONS_SETTINGS_ACCESSIBILITY_SCREEN_MAGNIFIER_DESCRIPTION" desc="In the settings tab, the text next to the dropdown for screen magnifier.">
         Enable screen magnifier
       </message>
+      <message name="IDS_OPTIONS_SETTINGS_ACCESSIBILITY_SCREEN_MAGNIFIER_OFF" desc="In the settings tab, the option indication the screen magnifier is off.">
+        Off
+      </message>
+      <message name="IDS_OPTIONS_SETTINGS_ACCESSIBILITY_SCREEN_MAGNIFIER_FULL" desc="In the settings tab, the option indication the screen magnifier is set to full.">
+        Full
+      </message>
+      <message name="IDS_OPTIONS_SETTINGS_ACCESSIBILITY_SCREEN_MAGNIFIER_PARTIAL" desc="In the settings tab, the option indication the screen magnifier is set to partial.">
+        Partial
+      </message>
       <message name="IDS_OPTIONS_SETTINGS_ACCESSIBILITY_VIRTUAL_KEYBOARD_DESCRIPTION" desc="In the settings tab, the text next to the checkbox for virtual keyboard.">
         Enable virtual keyboard
       </message>