Material PDF: Add metrics to count usage of PDF title and bookmarks

Support for these metadata fields was added recently, this will allow us to
determine how commonly these features are used.

BUG=439114

Review URL: https://codereview.chromium.org/1403833002

Cr-Commit-Position: refs/heads/master@{#354413}

1 files changed, 19 insertions, 2 deletions

diff --git a/pdf/out_of_process_instance.cc b/pdf/out_of_process_instance.cc
index cfa11ba..12aad3c 100644
--- a/pdf/out_of_process_instance.cc
+++ b/pdf/out_of_process_instance.cc
@@ -156,6 +156,14 @@ namespace {
 
 static const char kPPPPdfInterface[] = PPP_PDF_INTERFACE_1;
 
+// Used for UMA. Do not delete entries, and keep in sync with histograms.xml.
+enum PDFFeatures {
+  LOADED_DOCUMENT = 0,
+  HAS_TITLE = 1,
+  HAS_BOOKMARKS = 2,
+  FEATURES_COUNT
+};
+
 PP_Var GetLinkAtPosition(PP_Instance instance, PP_Point point) {
   pp::Var var;
   void* object = pp::Instance::GetPerInstanceObject(instance, kPPPPdfInterface);
@@ -1101,6 +1109,8 @@ void OutOfProcessInstance::DocumentLoadComplete(int page_count) {
   DCHECK(document_load_state_ == LOAD_STATE_LOADING);
   document_load_state_ = LOAD_STATE_COMPLETE;
   UserMetricsRecordAction("PDF.LoadSuccess");
+  uma_.HistogramEnumeration("PDF.DocumentFeature", LOADED_DOCUMENT,
+                            FEATURES_COUNT);
 
   // Note: If we are in print preview mode the scroll location is retained
   // across document loads so we don't want to scroll again and override it.
@@ -1112,10 +1122,17 @@ void OutOfProcessInstance::DocumentLoadComplete(int page_count) {
   pp::VarDictionary metadata_message;
   metadata_message.Set(pp::Var(kType), pp::Var(kJSMetadataType));
   std::string title = engine_->GetMetadata("Title");
-  if (!base::TrimWhitespace(base::UTF8ToUTF16(title), base::TRIM_ALL).empty())
+  if (!base::TrimWhitespace(base::UTF8ToUTF16(title), base::TRIM_ALL).empty()) {
     metadata_message.Set(pp::Var(kJSTitle), pp::Var(title));
+    uma_.HistogramEnumeration("PDF.DocumentFeature", HAS_TITLE, FEATURES_COUNT);
+  }
 
-  metadata_message.Set(pp::Var(kJSBookmarks), engine_->GetBookmarks());
+  pp::VarArray bookmarks = engine_->GetBookmarks();
+  metadata_message.Set(pp::Var(kJSBookmarks), bookmarks);
+  if (bookmarks.GetLength() > 0) {
+    uma_.HistogramEnumeration("PDF.DocumentFeature", HAS_BOOKMARKS,
+                              FEATURES_COUNT);
+  }
   PostMessage(metadata_message);
 
   pp::VarDictionary progress_message;