Original patch from issue 570048

chrome/browser/tab_contents/tab_contents.cc

 // Copyright (c) 2011 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 "chrome/browser/tab_contents/tab_contents.h"
 
 #include <cmath>
 
 #include "base/auto_reset.h"
 #include "base/metrics/histogram.h"
@@ skipping 1430 matching lines @@
 
 void TabContents::UpdateHistoryPageTitle(const NavigationEntry& entry) {
   if (profile()->IsOffTheRecord())
     return;
 
   HistoryService* hs = profile()->GetHistoryService(Profile::IMPLICIT_ACCESS);
   if (hs)
     hs->SetPageTitle(entry.virtual_url(), entry.title());
 }
 
+int TabContents::SetZoomLevel(double zoom_level) {
+  static int request_id = -1;
+
+  ++request_id;

[Aaron Boodman, 2011/02/07 09:26:55]

Chromium style forbids post-increment.

+  render_view_host()->SetZoomLevel(request_id, zoom_level);
+  return request_id;
+}
+
 double TabContents::GetZoomLevel() const {
   HostZoomMap* zoom_map = profile()->GetHostZoomMap();
   if (!zoom_map)
     return 0;
 
   double zoom_level;
   if (temporary_zoom_settings_) {
     zoom_level = zoom_map->GetTemporaryZoomLevel(
         GetRenderProcessHost()->id(), render_view_host()->routing_id());
   } else {
     zoom_level = zoom_map->GetZoomLevel(GetURL());
   }
   return zoom_level;
 }
 
-int TabContents::GetZoomPercent(bool* enable_increment,
+int TabContents::SetZoomPercent(double zoom_percent) {
+  double zoom_level;
+  zoom_level = WebKit::WebView::zoomFactorToZoomLevel(zoom_percent / 100);
+  return SetZoomLevel(zoom_level);
+}
+
+double TabContents::GetZoomPercent(bool* enable_increment,
                                 bool* enable_decrement) {
   *enable_decrement = *enable_increment = false;
-  int percent = static_cast<int>(
-      WebKit::WebView::zoomLevelToZoomFactor(GetZoomLevel()) * 100);
+  double percent = 0.0;
+  percent = WebKit::WebView::zoomLevelToZoomFactor(GetZoomLevel()) * 100;
   *enable_decrement = percent > minimum_zoom_percent_;
   *enable_increment = percent < maximum_zoom_percent_;
   return percent;
 }
 
 void TabContents::ViewSource() {
   if (!delegate_)
     return;
 
   NavigationEntry* active_entry = controller().GetActiveEntry();
@@ skipping 410 matching lines @@
 void TabContents::UpdateAlternateErrorPageURL() {
   GURL url = GetAlternateErrorPageURL();
   render_view_host()->SetAlternateErrorPageURL(url);
 }
 
 void TabContents::UpdateWebPreferences() {
   render_view_host()->UpdateWebPreferences(GetWebkitPrefs());
 }
 
 void TabContents::UpdateZoomLevel() {
-  render_view_host()->SetZoomLevel(GetZoomLevel());
+  SetZoomLevel(GetZoomLevel());
 }
 
 void TabContents::UpdateMaxPageIDIfNecessary(SiteInstance* site_instance,
                                              RenderViewHost* rvh) {
   // If we are creating a RVH for a restored controller, then we might
   // have more page IDs than the SiteInstance's current max page ID.  We must
   // make sure that the max page ID is larger than any restored page ID.
   // Note that it is ok for conflicting page IDs to exist in another tab
   // (i.e., NavigationController), but if any page ID is larger than the max,
   // the back/forward list will get confused.
@@ skipping 1216 matching lines @@
 }
 
 bool TabContents::MaybeUsePreloadedPage(const GURL& url) {
   PrerenderManager* pm = profile()->GetPrerenderManager();
   if (pm != NULL) {
     if (pm->MaybeUsePreloadedPage(this, url))
       return true;
   }
   return false;
 }