Add setting to isolate zoom changes by default.

content/browser/host_zoom_map_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/host_zoom_map_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/strings/string_piece.h"
@@ skipping 125 matching lines @@
   for (SchemeHostZoomLevels::const_iterator i(copy->
            scheme_host_zoom_levels_.begin());
        i != copy->scheme_host_zoom_levels_.end(); ++i) {
     scheme_host_zoom_levels_[i->first] = HostZoomLevels();
     scheme_host_zoom_levels_[i->first].
         insert(i->second.begin(), i->second.end());
   }
   default_zoom_level_ = copy->default_zoom_level_;
 }
 
+void HostZoomMapImpl::PreserveTemporaryZoomLevelFrom(
+    const HostZoomMap* copy_interface, RenderFrameHost* old_host,
+    RenderFrameHost* new_host) {
+  const HostZoomMapImpl* copy =
+      static_cast<const HostZoomMapImpl*>(copy_interface);
+  const RenderViewHost* old_view_host = old_host->GetRenderViewHost();
+  const RenderViewHost* new_view_host = new_host->GetRenderViewHost();
+
+  DCHECK(copy->UsesTemporaryZoomLevel(old_view_host->GetProcess()->GetID(),
+                                      old_view_host->GetRoutingID()));
+
+  const double level = copy->GetTemporaryZoomLevel(
+      old_view_host->GetProcess()->GetID(), old_view_host->GetRoutingID());
+  SetTemporaryZoomLevel(
+      new_view_host->GetProcess()->GetID(), new_view_host->GetRoutingID(),
+      level);
+}
+
 double HostZoomMapImpl::GetZoomLevelForHost(const std::string& host) const {
   base::AutoLock auto_lock(lock_);
   return GetZoomLevelForHostInternal(host);
 }
 
 double HostZoomMapImpl::GetZoomLevelForHostInternal(
     const std::string& host) const {
   HostZoomLevels::const_iterator i(host_zoom_levels_.find(host));
   return (i == host_zoom_levels_.end()) ? default_zoom_level_ : i->second;
 }
@@ skipping 395 matching lines @@
   double error_page_zoom_level = GetZoomLevelForHost(host);
 
   SendZoomLevelChange(std::string(), host, error_page_zoom_level);
 }
 
 HostZoomMapImpl::~HostZoomMapImpl() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 }
 
 }  // namespace content