Adding the Previews infobar to pages that show a client LoFi image

chrome/browser/previews/previews_infobar_delegate.h

 // Copyright 2016 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.
 
 #ifndef CHROME_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_DELEGATE_H_
 #define CHROME_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_DELEGATE_H_
 
 #include "base/callback.h"
 #include "base/strings/string16.h"
 #include "components/infobars/core/confirm_infobar_delegate.h"
 
 namespace content {
 class WebContents;
 }
 
 // Shows an infobar that lets the user know that a preview page has been loaded,
 // and gives the user a link to reload the original page. This infobar will only
 // be shown once per page load. Records UMA data for user interactions with the
 // infobar.
 class PreviewsInfoBarDelegate : public ConfirmInfoBarDelegate {
  public:
   // The type of the infobar. It controls the strings and what UMA data is
   // recorded for the infobar.
+  // TODO(ryansturm): Combine PreviewsInfoBarType with previews::PreviewsType.
+  // crbug.com/704335
   enum PreviewsInfoBarType {
-    LOFI,      // Server-side image replacement.
-    LITE_PAGE, // Server-side page rewrite.
-    OFFLINE,   // Offline copy of the page.
+    LOFI,         // Server-side image replacement.
+    LITE_PAGE,    // Server-side page rewrite.
+    OFFLINE,      // Offline copy of the page.
+    CLIENT_LOFI,  // Client-side image replacement.

[sclittle, 2017/05/03 18:40:21]

Since both Server LoFi and Client LoFi will often be used at the same time on
the same page, what do we gain from having a separate CLIENT_LOFI value here?

Could we just simplify this and make both kinds of LoFi use the same infobar
type?

[RyanSturm, 2017/05/03 18:48:52]

I'd prefer to know the difference between the opt out rates of server LoFi vs
Client LoFi since they do actually have differences when it comes to sprite
detection, etc. Does Client LoFi only apply to HTTPS within a page load or can
it also be used on HTTP resources?

[sclittle, 2017/05/03 19:02:47]

Client LoFi tries to target all http:// and https:// images that don't look like
they're already handled by another kind of preview.

In practice, this means that it targets no images when Server Lite Pages is
used, it targets only https:// images when Server LoFi is enabled for the page,
and it targets both http:// and https:// images otherwise.

See
https://docs.google.com/document/d/1rWCON90u3j8JtgRk_SB6JTOIeKqp4rQjlRfj_W1zc...
for more info.

   };
 
   typedef base::Callback<void(bool opt_out)> OnDismissPreviewsInfobarCallback;
 
   // Actions on the previews infobar. This enum must remain synchronized with
   // the enum of the same name in metrics/histograms/histograms.xml.
   enum PreviewsInfoBarAction {
     INFOBAR_SHOWN = 0,
     INFOBAR_LOAD_ORIGINAL_CLICKED = 1,
     INFOBAR_DISMISSED_BY_USER = 2,
@@ skipping 34 matching lines @@
   mutable PreviewsInfoBarAction infobar_dismissed_action_;
 
   const base::string16 message_text_;
 
   OnDismissPreviewsInfobarCallback on_dismiss_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(PreviewsInfoBarDelegate);
 };
 
 #endif  // CHROME_BROWSER_PREVIEWS_PREVIEWS_INFOBAR_DELEGATE_H_