Introduce ChromeZoomLevelPref, make zoom level prefs independent of profile prefs.

chrome/browser/ui/pdf/pdf_unsupported_feature.cc

Index: chrome/browser/ui/pdf/pdf_unsupported_feature.cc
diff --git a/chrome/browser/ui/pdf/pdf_unsupported_feature.cc b/chrome/browser/ui/pdf/pdf_unsupported_feature.cc
index d1a351dfa85cb9e18d3caefbe6019275b7e4ff81..d8ad0ebbcc33ca9284921725ceb075cb9211304d 100644
--- a/chrome/browser/ui/pdf/pdf_unsupported_feature.cc
+++ b/chrome/browser/ui/pdf/pdf_unsupported_feature.cc
@@ -18,6 +18,7 @@
 #include "chrome/grit/generated_resources.h"
 #include "components/pdf/browser/open_pdf_in_reader_prompt_client.h"
 #include "components/pdf/browser/pdf_web_contents_helper.h"
+#include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/interstitial_page.h"
 #include "content/public/browser/interstitial_page_delegate.h"
 #include "content/public/browser/navigation_details.h"
@@ -28,6 +29,7 @@
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/user_metrics.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/renderer_preferences.h"
 #include "grit/browser_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -219,6 +221,11 @@ class PDFUnsupportedFeatureInterstitial
     Profile* profile =
         Profile::FromBrowserContext(web_contents_->GetBrowserContext());
     renderer_preferences_util::UpdateFromSystemSettings(prefs, profile);
+    // TODO(wjmaclean): Convert this to use the HostZoomMap for the WebContents
+    // when HostZoomMap moves to StoragePartition.
+    prefs->default_zoom_level =
+        content::HostZoomMap::GetDefaultForBrowserContext(profile)
+            ->GetDefaultZoomLevel();
   }
 
  private: