Update entry page type to include error pages when appropriate.

chrome/browser/ui/zoom/zoom_controller.cc

Index: chrome/browser/ui/zoom/zoom_controller.cc
diff --git a/chrome/browser/ui/zoom/zoom_controller.cc b/chrome/browser/ui/zoom/zoom_controller.cc
index 95ab757f3f7d5bf75cc7c3956e7045ae7fb3afae..45b087588422f4aa7e43ecaff35b2339ffb9538f 100644
--- a/chrome/browser/ui/zoom/zoom_controller.cc
+++ b/chrome/browser/ui/zoom/zoom_controller.cc
@@ -12,6 +12,7 @@
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/page_type.h"
 #include "content/public/common/page_zoom.h"
 #include "extensions/common/extension.h"
 #include "grit/theme_resources.h"
@@ -78,10 +79,14 @@ bool ZoomController::SetZoomLevel(double zoom_level) {
 bool ZoomController::SetZoomLevelByExtension(
     double zoom_level,
     const scoped_refptr<const extensions::Extension>& extension) {
+  bool is_error_page =
+      web_contents()->GetController().GetLastCommittedEntry()->GetPageType() ==
+      content::PAGE_TYPE_ERROR;
   // Cannot zoom in disabled mode. Also, don't allow changing zoom level on
-  // a crashed tab.
+  // a crashed tab or an error page.

[Charlie Reis, 2014/09/24 16:43:43]

Sanity check: I realize that changing the zoom level does nothing on error pages
today, and this change makes that explicit (e.g., disabling the zoom bubble,
etc).  An alternate fix would make the error message actually zoom, which might
be better for accessibility.  Is that worth considering, or are there reasons
not to do that?

(Either way, we'll need the PAGE_TYPE_ERROR fixes, which are great regardless.)

Oh, and it looks like interstitial pages have this same issue-- zooming them
doesn't affect the interstitial but does show the bubble.  I wonder if that's
affecting the destination site if you end up proceeding through the
interstitial?

[wjmaclean, 2014/09/24 17:59:11]

Good observation ... let's do this: make error & interstitial pages not zoom
(for now), and get the UX folks involved. But we need to proceed carefully,
since when an error page is showing, zooming will affect the intended url, not
just the error page, so we would need to think about how to handle that
properly.

[Charlie Reis, 2014/09/24 18:08:52]

Sounds perfect-- thanks.

   if (zoom_mode_ == ZOOM_MODE_DISABLED ||
-      !web_contents()->GetRenderViewHost()->IsRenderViewLive())
+      !web_contents()->GetRenderViewHost()->IsRenderViewLive() ||
+      is_error_page)
     return false;
 
   // Store extension data so that |extension| can be attributed when the zoom