Add UMA for popup overlays removed from saved MHTML page

third_party/WebKit/Source/web/WebFrameSerializer.cpp

Index: third_party/WebKit/Source/web/WebFrameSerializer.cpp
diff --git a/third_party/WebKit/Source/web/WebFrameSerializer.cpp b/third_party/WebKit/Source/web/WebFrameSerializer.cpp
index 8dd4fd826ff07edc13d1bf0c8f2067da67d865fd..65b672735241165c428d7db46da6c389b6bc88f5 100644
--- a/third_party/WebKit/Source/web/WebFrameSerializer.cpp
+++ b/third_party/WebKit/Source/web/WebFrameSerializer.cpp
@@ -105,11 +105,12 @@ class MHTMLFrameSerializerDelegate final : public FrameSerializer::Delegate {
                                                 Vector<Attribute>*);
 
   WebFrameSerializer::MHTMLPartsGenerationDelegate& web_delegate_;
+  bool has_popup_overlays_skipped_;
 };
 
 MHTMLFrameSerializerDelegate::MHTMLFrameSerializerDelegate(
     WebFrameSerializer::MHTMLPartsGenerationDelegate& web_delegate)
-    : web_delegate_(web_delegate) {}
+    : web_delegate_(web_delegate), has_popup_overlays_skipped_(false) {}
 
 bool MHTMLFrameSerializerDelegate::ShouldIgnoreElement(const Element& element) {
   if (ShouldIgnoreHiddenElement(element))
@@ -170,6 +171,12 @@ bool MHTMLFrameSerializerDelegate::ShouldIgnorePopupOverlayElement(
   if (box->Style()->ZIndex() < kPopupOverlayZIndexThreshold)
     return false;
 
+  if (!has_popup_overlays_skipped_) {
+    has_popup_overlays_skipped_ = true;
+    UMA_HISTOGRAM_BOOLEAN(
+        "PageSerialization.MhtmlGeneration.PopupOverlaySkippedCount", true);

[Steven Holte, 2017/04/27 23:41:53]

Actually the name of this histogram and how you are recording it are a bit
strange.  Count in the name implies that this histogram would be recording the
number of times this was skipped, but you are instead recording that it was
skipped.

I'd suggest changing the name to
PageSerialization.MhtmlGeneration.PopupOverlaySkipped and probably recording a
False case for a reasonable baseline.

[jianli, 2017/04/28 00:52:07]

Done.

+  }
+
   return true;
 }