Re-introduce the partial magnifier

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 1fc2934ab22d642e1a6f637cd3403794f4b03262..b257021eab2c4c97637b6382f15cdb0701302531 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -734,6 +734,10 @@ const char kSpokenFeedbackEnabled[] = "settings.accessibility";
 const char kHighContrastEnabled[] = "settings.a11y.high_contrast_enabled";
 // A boolean pref which determines whether screen magnifier is enabled.
 const char kScreenMagnifierEnabled[] = "settings.a11y.screen_magnifier";
+// A string pref which determines what type of scre en magnifier is enabled.
+// Note that: 'screen_magnifier_type' had been used as string pref. Hence,
+// we are using another name pref here.
+const char kScreenMagnifierType[] = "settings.a11y.screen_magnifier_type2";
 // A double pref which determines a zooming scale of the screen magnifier.
 const char kScreenMagnifierScale[] = "settings.a11y.screen_magnifier_scale";
 // A boolean pref which determines whether virtual keyboard is enabled.