Add UMA for documents calling window.print().

content/renderer/render_view_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/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <memory>
 
@@ skipping 1613 matching lines @@
   }
   return widget->GetWebWidget();
 }
 
 WebStorageNamespace* RenderViewImpl::createSessionStorageNamespace() {
   CHECK(session_storage_namespace_id_ != kInvalidSessionStorageNamespaceId);
   return new WebStorageNamespaceImpl(session_storage_namespace_id_);
 }
 
 void RenderViewImpl::printPage(WebLocalFrame* frame) {
+  UMA_HISTOGRAM_BOOLEAN("Printing.InitiatedByScript", frame->top() == frame);
+
+  // Logging whether the top frame is remote is sufficient in this case. If
+  // the top frame is local, the printing code will function correctly and
+  // the frame itself will be printed, so the cases this histogram tracks is
+  // where printing of a subframe will fail as of now.
+  UMA_HISTOGRAM_BOOLEAN("Printing.OutOfProcessSubframe",
+                        frame->top()->isWebRemoteFrame());

[Lei Zhang, 2016/10/11 23:42:59]

frame->top() won't ever be a nullptr, right?

[nasko, 2016/10/11 23:44:17]

Yes, it should never be null, but can be either local or remote. We care about
the cases that the top level frame is a remote one.

[Lei Zhang, 2016/10/11 23:51:14]

Acknowledged.

+
   FOR_EACH_OBSERVER(RenderViewObserver, observers_,
                     PrintPage(frame, input_handler().handling_input_event()));
 }
 
 bool RenderViewImpl::enumerateChosenDirectory(
     const WebString& path,
     WebFileChooserCompletion* chooser_completion) {
   int id = enumeration_completion_id_++;
   enumeration_completions_[id] = chooser_completion;
   return Send(new ViewHostMsg_EnumerateDirectory(
@@ skipping 1380 matching lines @@
   if (IsUseZoomForDSFEnabled()) {
     webview()->setZoomFactorForDeviceScaleFactor(device_scale_factor_);
   } else {
     webview()->setDeviceScaleFactor(device_scale_factor_);
   }
   webview()->settings()->setPreferCompositingToLCDTextEnabled(
       PreferCompositingToLCDText(compositor_deps_, device_scale_factor_));
 }
 
 }  // namespace content