PDF: Add UMA to track embedded PDF triggered drive-by downloads.

chrome/renderer/plugins/plugin_uma.h

 // Copyright (c) 2011 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_RENDERER_PLUGINS_PLUGIN_UMA_H_
 #define CHROME_RENDERER_PLUGINS_PLUGIN_UMA_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 26 matching lines @@
     UNSUPPORTED_MIMETYPE,
     UNSUPPORTED_EXTENSION,
     // NOTE: Add new unsupported types only immediately above this line.
     BROWSER_PLUGIN = 10,
     SHOCKWAVE_FLASH,
     WIDEVINE_CDM,
     // NOTE: Add new plugin types only immediately above this line.
     PLUGIN_TYPE_MAX
   };
 
-  // Must be kept in sync with PDFLoadStatus enum in histograms.xml.
-  // This enum should be treated as append-only.
-  enum PDFLoadStatus {
-    LOADED_FULL_PAGE_PDF_WITH_PDFIUM = 0,
-    LOADED_EMBEDDED_PDF_WITH_PDFIUM = 1,
-    SHOWED_DISABLED_PLUGIN_PLACEHOLDER_FOR_EMBEDDED_PDF = 2,
-    PDF_LOAD_STATUS_COUNT
-  };
-
   // Sends UMA data, i.e. plugin's type.
   class UMASender {
    public:
     virtual ~UMASender() {}
     virtual void SendPluginUMA(ReportType report_type,
                                PluginType plugin_type) = 0;
   };
 
   // Returns singleton instance.
   static PluginUMAReporter* GetInstance();
 
-  static void ReportPDFLoadStatus(PDFLoadStatus status);
-
   void ReportPluginMissing(const std::string& plugin_mime_type,
                            const GURL& plugin_src);
 
   void ReportPluginDisabled(const std::string& plugin_mime_type,
                             const GURL& plugin_src);
 
  private:
   friend struct base::DefaultSingletonTraits<PluginUMAReporter>;
   friend class PluginUMATest;
 
@@ skipping 14 matching lines @@
   PluginType SrcToPluginType(const GURL& src);
   // Converts plugin's mime type to plugin type.
   PluginType MimeTypeToPluginType(const std::string& mime_type);
 
   std::unique_ptr<UMASender> report_sender_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginUMAReporter);
 };
 
 #endif  // CHROME_RENDERER_PLUGINS_PLUGIN_UMA_H_