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..5ef82d9df3d67524d1c96d63d1e5bc518fe2307e 100644
--- a/chrome/browser/ui/prefs/prefs_tab_helper.cc
+++ b/chrome/browser/ui/prefs/prefs_tab_helper.cc
@@ -15,6 +15,8 @@
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/renderer_preferences_util.h"
+#include "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
+#include "chrome/browser/ui/zoom/zoom_controller.h"
 #include "chrome/common/pref_font_webkit_names.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/pref_names_util.h"
@@ -24,6 +26,7 @@
 #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"
@@ -318,10 +321,19 @@ PrefsTabHelper::PrefsTabHelper(WebContents* contents)
   PrefService* prefs = GetProfile()->GetPrefs();
   pref_change_registrar_.Init(prefs);
   if (prefs) {
+    // TODO(wjmaclean): Convert this to use the content-specific zoom-level
+    // prefs when HostZoomMap moves to StoragePartition.
+    chrome::ChromeZoomLevelPrefs* zoom_level_prefs =
+        GetProfile()->GetZoomLevelPrefs();
+
     base::Closure renderer_callback = base::Bind(
         &PrefsTabHelper::UpdateRendererPreferences, base::Unretained(this));
+    // Not all tests will create zoom_level_prefs.

[battre, 2014/10/08 11:27:10]

Also no incognito tabs. Are you sure this is ok?

[wjmaclean, 2014/10/10 14:40:29]

I think so. Certainly the zoom levels in incognito are explicitly set to not
update the existing per-host prefs, and you can't edit any zoom settings in an
incognito window.

In this file, if the zoom level prefs don't exist, then all that happens is no
callback is registered on pref changes, but that's ok for everything except
default-zoom level. But in incognito mode changes to default zoom level
propagate to render views via a different mechanism, so this CL seems to
preserve that behaviour too. In guest mode, the changes don't propagate anyways.

I have updated the comment above though to indicate that incognito windows won't
have one either.

+    if (zoom_level_prefs) {
+      default_zoom_level_subscription_ =
+          zoom_level_prefs->RegisterDefaultZoomLevelCallback(renderer_callback);
+    }
     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);
 
@@ -359,11 +371,15 @@ 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(),
+                                                      web_contents_);
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && defined(ENABLE_THEMES)
-  registrar_.Add(this, chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
+  registrar_.Add(this,
+                 chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
                  content::Source<ThemeService>(
                      ThemeServiceFactory::GetForProfile(GetProfile())));
 #endif
@@ -567,8 +583,10 @@ void PrefsTabHelper::UpdateWebPreferences() {
 }
 
 void PrefsTabHelper::UpdateRendererPreferences() {
+  content::RendererPreferences* prefs =
+      web_contents_->GetMutableRendererPrefs();
   renderer_preferences_util::UpdateFromSystemSettings(
-      web_contents_->GetMutableRendererPrefs(), GetProfile());
+      prefs, GetProfile(), web_contents_);
   web_contents_->GetRenderViewHost()->SyncRendererPrefs();
 }