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

chrome/common/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/buildflag_header.gni")
 import("//build/util/process_version.gni")
 import("//chrome/common/features.gni")
 import("//chrome/process_version_rc_template.gni")  # For branding_file_path.
 import("//extensions/features/features.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
@@ skipping 101 matching lines @@
     "page_load_metrics/page_load_metrics_messages.h",
     "page_load_metrics/page_load_metrics_param_traits.cc",
     "page_load_metrics/page_load_metrics_param_traits.h",
     "page_load_metrics/page_load_timing.cc",
     "page_load_metrics/page_load_timing.h",
     "page_load_metrics/page_track_decider.cc",
     "page_load_metrics/page_track_decider.h",
     "partial_circular_buffer.cc",
     "partial_circular_buffer.h",
     "pause_tabs_field_trial.h",
+    "pdf_uma.cc",
+    "pdf_uma.h",
     "pref_names_util.cc",
     "pref_names_util.h",
     "prerender_messages.h",
     "prerender_types.h",
     "profiling.cc",
     "profiling.h",
     "ref_counted_util.h",
     "render_messages.h",
     "resource_usage_reporter_type_converters.cc",
     "resource_usage_reporter_type_converters.h",
@@ skipping 615 matching lines @@
 
 mojom("page_load_metrics_mojom") {
   sources = [
     "page_load_metrics/page_load_metrics.mojom",
   ]
 
   public_deps = [
     "//mojo/common:common_custom_types",
   ]
 }