Add InfoBar delegate for previews

chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_io_data.cc

Index: chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_io_data.cc
diff --git a/chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_io_data.cc b/chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_io_data.cc
index a75e05fc74d1e1923593810a0a1e0ccdfe57b1d3..79213d08407a89407ffec77c8e12e41917895f59 100644
--- a/chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_io_data.cc
+++ b/chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_io_data.cc
@@ -11,6 +11,7 @@
 #include "build/build_config.h"
 #include "chrome/browser/net/spdyproxy/chrome_data_use_group_provider.h"
 #include "chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_settings.h"
+#include "chrome/browser/previews/previews_infobar_delegate.h"
 #include "chrome/common/channel_info.h"
 #include "chrome/common/chrome_content_client.h"
 #include "chrome/common/pref_names.h"
@@ -25,7 +26,6 @@
 
 #if defined(OS_ANDROID)
 #include "base/android/build_info.h"
-#include "chrome/browser/android/tab_android.h"
 #endif
 
 namespace content {
@@ -43,11 +43,9 @@ namespace {
 void OnLoFiResponseReceivedOnUI(content::WebContents* web_contents,
                                 bool is_preview) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-#if defined(OS_ANDROID)
-  TabAndroid* tab = TabAndroid::FromWebContents(web_contents);
-  if (tab)
-    tab->OnLoFiResponseReceived(is_preview);
-#endif
+  PreviewsInfoBarDelegate::Create(web_contents,

[Peter Kasting, 2016/08/23 19:48:17]

Is this code accessible on non-Android builds?

Right now the resources, enum values, implementation locations, etc. are all
done in cross-platform ways, but it seems as if this is maybe an
Android-specific thing.  If it is, we want to make that as clear as possible and
avoid compiling in this stuff for the other platforms.

[megjablon, 2016/08/23 23:54:16]

Right now we can enable previews on desktop via a command line flag and
chrome://flags. We've always had the context menu items for it, but not the
infobar. bengr@ what do you think about having this on desktop? Will we need it
from a product standpoint? It's particularly useful for testing and debugging.

[Peter Kasting, 2016/08/24 03:18:27]

I am OK with resolving this issue as a follow-up, but do strive to resolve it --
we've had a lot of confusion and trouble over the years with
seemingly-cross-platform code that turned out to be Android-only in practice, so
either being clearly Android-only or else actually working on all platforms are
better end states.

[megjablon, 2016/08/24 21:44:29]

The code fully works on all platforms so it doesn't fall into the
seemingly-cross-platform bucket. This UI was the only part of the feature living
in Android before and now we can display it on desktop too. 

+                                  is_preview ? PreviewsInfoBarDelegate::PREVIEW
+                                             : PreviewsInfoBarDelegate::LOFI);
 }
 
 } // namespace