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 451 matching lines @@
   }
 
   if (is_mac) {
     sources -= [ "channel_info_posix.cc" ]
     public_deps += [
       "//third_party/google_toolbox_for_mac",
       "//third_party/mach_override",
     ]
   }
 
+  if (enable_pdf) {

[Lei Zhang, 2017/05/24 22:39:21]

You are using BUILDFLAG(ENABLE_PLUGINS) in the C++ code. Is that the same as
enable_pdf?

[tommycli, 2017/05/25 18:16:37]

Actually i have no idea what i was thinking. i specifically want this enabled
whether or not there's PDF or plugins.

+    sources += [
+      "pdf_uma.cc",
+      "pdf_uma.h",
+    ]
+  }
   if (enable_plugins) {
     sources += [
       "pepper_flash.cc",
       "pepper_flash.h",
       "plugin_utils.cc",
       "plugin_utils.h",
       "ppapi_utils.cc",
       "ppapi_utils.h",
     ]
     public_deps += [ "//third_party/adobe/flash:flapper_version_h" ]
@@ skipping 265 matching lines @@
 
 mojom("page_load_metrics_mojom") {
   sources = [
     "page_load_metrics/page_load_metrics.mojom",
   ]
 
   public_deps = [
     "//mojo/common:common_custom_types",
   ]
 }