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

chrome/browser/ui/prefs/prefs_tab_helper.cc

Index: chrome/browser/ui/prefs/prefs_tab_helper.cc
diff --git a/chrome/browser/ui/prefs/prefs_tab_helper.cc b/chrome/browser/ui/prefs/prefs_tab_helper.cc
index 816e08b60f60092d0f97371f9dc9d6261dbc86bb..e80e41d726feb11718ce188828cd76ca92b730f9 100644
--- a/chrome/browser/ui/prefs/prefs_tab_helper.cc
+++ b/chrome/browser/ui/prefs/prefs_tab_helper.cc
@@ -20,10 +20,12 @@
 #include "chrome/common/pref_names_util.h"
 #include "chrome/grit/locale_settings.h"
 #include "components/pref_registry/pref_registry_syncable.h"
+#include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/renderer_preferences.h"
 #include "content/public/common/web_preferences.h"
 #include "grit/platform_locale_settings.h"
 #include "third_party/icu/source/common/unicode/uchar.h"
@@ -315,13 +317,37 @@ void OverrideFontFamily(WebPreferences* prefs,
 PrefsTabHelper::PrefsTabHelper(WebContents* contents)
     : web_contents_(contents),
       weak_ptr_factory_(this) {
+  // TODO(wjmaclean): Convert this to use the content-specific zoom-level
+  // prefs when HostZoomMap moves to StoragePartition.
+  PrefService* zoom_level_prefs = GetProfile()->GetZoomLevelPrefs();
+  if (zoom_level_prefs) {
+    zoom_level_pref_change_registrar_.Init(zoom_level_prefs);
+    base::Closure renderer_callback = base::Bind(
+        &PrefsTabHelper::UpdateRendererPreferences, base::Unretained(this));
+    zoom_level_pref_change_registrar_.Add(prefs::kDefaultZoomLevel,
+                                          renderer_callback);
+    if (zoom_level_prefs->GetInitializationStatus() ==
+        PrefService::INITIALIZATION_STATUS_WAITING) {
+      // Unlike per-profile prefs, which are guaranteed to have initialized by
+      // the time we get here, zoom-level prefs may not have
+      // completed their initialization. In this case, we need to re-sync the
+      // renderer prefs once their initialization completes so that the default
+      // zoom level information is updated.
+      // TODO(wjmaclean) We need to determine if there are possible lifetime
+      // issues here, namely, can 'this' disappear before the zoom_level_prefs
+      // have finished initializing, causing a stale pointer via the callback?
+      zoom_level_prefs->AddPrefInitObserver(
+          base::Bind(&PrefsTabHelper::UpdateAfterZoomLevelPrefsInitialized,
+                     base::Unretained(this)));
+    }
+  }
+
   PrefService* prefs = GetProfile()->GetPrefs();
   pref_change_registrar_.Init(prefs);
   if (prefs) {
     base::Closure renderer_callback = base::Bind(
         &PrefsTabHelper::UpdateRendererPreferences, base::Unretained(this));
     pref_change_registrar_.Add(prefs::kAcceptLanguages, renderer_callback);
-    pref_change_registrar_.Add(prefs::kDefaultZoomLevel, renderer_callback);
     pref_change_registrar_.Add(prefs::kEnableDoNotTrack, renderer_callback);
     pref_change_registrar_.Add(prefs::kEnableReferrers, renderer_callback);
 
@@ -359,8 +385,15 @@ PrefsTabHelper::PrefsTabHelper(WebContents* contents)
                                   webkit_callback);
   }
 
-  renderer_preferences_util::UpdateFromSystemSettings(
-      web_contents_->GetMutableRendererPrefs(), GetProfile());
+  content::RendererPreferences* render_prefs =
+      web_contents_->GetMutableRendererPrefs();
+  renderer_preferences_util::UpdateFromSystemSettings(render_prefs,
+                                                      GetProfile());
+  // TODO(wjmaclean): Convert this to use the HostZoomMap for the WebContents
+  // when HostZoomMap moves to StoragePartition.
+  render_prefs->default_zoom_level =
+      content::HostZoomMap::GetDefaultForBrowserContext(GetProfile())
+          ->GetDefaultZoomLevel();
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && defined(ENABLE_THEMES)
   registrar_.Add(this, chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
@@ -566,9 +599,19 @@ void PrefsTabHelper::UpdateWebPreferences() {
       web_contents_->GetRenderViewHost()->GetWebkitPreferences());
 }
 
+void PrefsTabHelper::UpdateAfterZoomLevelPrefsInitialized(bool success) {
+  if (success)
+    UpdateRendererPreferences();
+}
+
 void PrefsTabHelper::UpdateRendererPreferences() {
-  renderer_preferences_util::UpdateFromSystemSettings(
-      web_contents_->GetMutableRendererPrefs(), GetProfile());
+  content::RendererPreferences* prefs =
+      web_contents_->GetMutableRendererPrefs();
+  renderer_preferences_util::UpdateFromSystemSettings(prefs, GetProfile());
+  // TODO(wjmaclean): Convert this to use the HostZoomMap for the WebContents
+  // when HostZoomMap moves to StoragePartition.
+  prefs->default_zoom_level = content::HostZoomMap::GetDefaultForBrowserContext(
+                                  GetProfile())->GetDefaultZoomLevel();
   web_contents_->GetRenderViewHost()->SyncRendererPrefs();
 }