Add setting to isolate zoom changes by default.

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 64d3ff7ac0f52319d920dd75785d623211564063..328bfcddcc2735f6fed46bd20aa60e90cb35f388 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -8342,6 +8342,9 @@ I don't think this site should be blocked!
       <message name="IDS_ZOOMLEVELS_MANAGE_BUTTON" desc="Button on the Content Settings dialog that opens a dialog to manage your page zoom levels (zoom levels indicate that a page should be shown for example at 110% magnification).">
         Manage...
       </message>
+      <message name="IDS_ZOOMLEVELS_IGNORED_LABEL" desc="Label on the Zoom Level exceptions dialog that explains that any zoom level exceptions shown in the list above are not being applied when visiting the site as the user has deselected the setting to have zoom levels apply on a per-site basis (see IDS_OPTIONS_DEFAULT_ZOOM_SCOPE_LABEL) (zoom levels indicate that a page should be shown for example at 110% magnification).">
+        You have chosen to no longer remember zoom changes on a per-site basis. Any zoom levels shown here are not being used.
+      </message>
 
       <!-- Automatic updates -->
       <if expr="is_macosx">
@@ -11276,6 +11279,10 @@ I don't think this site should be blocked!
       <message name="IDS_OPTIONS_DEFAULT_ZOOM_LEVEL_LABEL" desc="The label of the 'Default Zoom Level' select menu">
         Page zoom:
       </message>
+      <!-- TODO Here's some sample copy. Any suggestions? -->
+      <message name="IDS_OPTIONS_DEFAULT_ZOOM_SCOPE_LABEL" desc="The label of the checkbox to enable/disable having the user's zoom changes apply to all tabs that navigate to the origin that was zoomed.">
+        When you change a page's zoom, remember the change for all pages on the same site
+      </message>
       <message name="IDS_OPTIONS_DEFAULT_FONT_SIZE_LABEL" desc="The label of the 'Default font size' select menu">
         Font size:
       </message>