Add setting to isolate zoom changes by default.

chrome/browser/ui/zoom/chrome_zoom_level_otr_delegate.cc

Index: chrome/browser/ui/zoom/chrome_zoom_level_otr_delegate.cc
diff --git a/chrome/browser/ui/zoom/chrome_zoom_level_otr_delegate.cc b/chrome/browser/ui/zoom/chrome_zoom_level_otr_delegate.cc
index 5092f549385ea777a8539c81655e69ca9ad97bf5..822fbe6147003a74496bbe87cf3b979f7e9e9e89 100644
--- a/chrome/browser/ui/zoom/chrome_zoom_level_otr_delegate.cc
+++ b/chrome/browser/ui/zoom/chrome_zoom_level_otr_delegate.cc
@@ -5,15 +5,35 @@
 #include "chrome/browser/ui/zoom/chrome_zoom_level_otr_delegate.h"
 
 #include "base/bind.h"
+#include "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
 #include "components/zoom/zoom_event_manager.h"
 
 ChromeZoomLevelOTRDelegate::ChromeZoomLevelOTRDelegate(
-    base::WeakPtr<zoom::ZoomEventManager> zoom_event_manager)
-    : zoom_event_manager_(zoom_event_manager), host_zoom_map_(nullptr) {}
+    base::WeakPtr<zoom::ZoomEventManager> zoom_event_manager,
+    ChromeZoomLevelPrefs* parent_zoom_level_prefs)
+    : zoom_event_manager_(zoom_event_manager), host_zoom_map_(nullptr),
+      parent_zoom_level_prefs_(parent_zoom_level_prefs) {}
 
 ChromeZoomLevelOTRDelegate::~ChromeZoomLevelOTRDelegate() {
 }
 
+bool ChromeZoomLevelOTRDelegate::GetIsOriginScopePref() const {
+  if (!parent_zoom_level_prefs_)

[wjmaclean, 2017/01/19 21:09:05]

Is this null for Guest browsing mode? If so, perhaps include a comment to
explain that.

[Kevin McNee, 2017/01/25 16:41:52]

This is no longer used.

+    return true;
+
+  // Just use the setting of the parent profile.
+  return parent_zoom_level_prefs_->GetIsOriginScopePref();
+}
+
+std::unique_ptr<ChromeZoomLevelOTRDelegate::DefaultZoomScopeSubscription>
+ChromeZoomLevelOTRDelegate::RegisterDefaultZoomScopeCallback(
+    const base::Closure& callback) {
+  if (!parent_zoom_level_prefs_)
+    return nullptr;
+
+  return parent_zoom_level_prefs_->RegisterDefaultZoomScopeCallback(callback);
+}
+
 void ChromeZoomLevelOTRDelegate::InitHostZoomMap(
     content::HostZoomMap* host_zoom_map) {
   // This init function must be called only once.