Extensions: Add metrics for Web Request API actions.

extensions/browser/api/web_request/web_request_api.cc

 // Copyright (c) 2012 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.
 
 #include "extensions/browser/api/web_request/web_request_api.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 69 matching lines @@
 namespace helpers = extension_web_request_api_helpers;
 namespace keys = extension_web_request_api_constants;
 
 namespace extensions {
 
 namespace declarative_keys = declarative_webrequest_constants;
 namespace web_request = api::web_request;
 
 namespace {
 
+// Describes the action taken by the Web Request API for a given stage of a web
+// request.
+// These values are written to logs.  New enum values can be added, but existing
+// enum values must never be renumbered or deleted and reused.
+enum RequestAction {
+  CANCEL = 0,
+  REDIRECT = 1,
+  MODIFY_REQUEST_HEADERS = 2,
+  MODIFY_RESPONSE_HEADERS = 3,
+  SET_AUTH_CREDENTIALS = 4,
+  MAX
+};
+
 const char kWebRequestEventPrefix[] = "webRequest.";
+const char kWebRequestActionUMA[] = "Extensions.WebRequestAction";
 
 // List of all the webRequest events.
 const char* const kWebRequestEvents[] = {
   keys::kOnBeforeRedirectEvent,
   web_request::OnBeforeRequest::kEventName,
   keys::kOnBeforeSendHeadersEvent,
   keys::kOnCompletedEvent,
   web_request::OnErrorOccurred::kEventName,
   keys::kOnSendHeadersEvent,
   keys::kOnAuthRequiredEvent,
@@ skipping 1708 matching lines @@
                                   blocked_request.net_log);
 
   WarningSet warnings;
   if (blocked_request.event == kOnBeforeRequest) {
     CHECK(!blocked_request.callback.is_null());
     helpers::MergeOnBeforeRequestResponses(
         blocked_request.request->url(), blocked_request.response_deltas,
         blocked_request.new_url, &warnings, blocked_request.net_log);
   } else if (blocked_request.event == kOnBeforeSendHeaders) {
     CHECK(!blocked_request.callback.is_null());
+    bool request_headers_modified = false;
     helpers::MergeOnBeforeSendHeadersResponses(
-        blocked_request.response_deltas,
-        blocked_request.request_headers,
-        &warnings,
-        blocked_request.net_log);
+        blocked_request.response_deltas, blocked_request.request_headers,
+        &warnings, blocked_request.net_log, &request_headers_modified);
+    if (request_headers_modified)

[Devlin, 2017/02/24 21:43:43]

nit: { } around multi-line if statement bodies.

[karandeepb, 2017/02/25 03:55:19]

Done.

+      UMA_HISTOGRAM_ENUMERATION(kWebRequestActionUMA,
+                                RequestAction::MODIFY_REQUEST_HEADERS,
+                                RequestAction::MAX);
   } else if (blocked_request.event == kOnHeadersReceived) {
     CHECK(!blocked_request.callback.is_null());
+    bool response_headers_modified = false;
     helpers::MergeOnHeadersReceivedResponses(
         blocked_request.request->url(), blocked_request.response_deltas,
         blocked_request.original_response_headers.get(),
         blocked_request.override_response_headers, blocked_request.new_url,
-        &warnings, blocked_request.net_log);
+        &warnings, blocked_request.net_log, &response_headers_modified);
+    if (response_headers_modified)
+      UMA_HISTOGRAM_ENUMERATION(kWebRequestActionUMA,
+                                RequestAction::MODIFY_RESPONSE_HEADERS,
+                                RequestAction::MAX);
   } else if (blocked_request.event == kOnAuthRequired) {
     CHECK(blocked_request.callback.is_null());
     CHECK(!blocked_request.auth_callback.is_null());
     credentials_set = helpers::MergeOnAuthRequiredResponses(
        blocked_request.response_deltas,
        blocked_request.auth_credentials,
        &warnings,
        blocked_request.net_log);
   } else {
     NOTREACHED();
   }
 
   SendMessages(browser_context, blocked_request, navigation_ui_data);
 
   if (!warnings.empty()) {
     BrowserThread::PostTask(
         BrowserThread::UI,
         FROM_HERE,
         base::Bind(&WarningService::NotifyWarningsOnUI,
                    browser_context, warnings));
   }
 
   if (canceled) {
     request_time_tracker_->SetRequestCanceled(request_id);
-  } else if (blocked_request.new_url &&
-             !blocked_request.new_url->is_empty()) {
+    UMA_HISTOGRAM_ENUMERATION(kWebRequestActionUMA, RequestAction::CANCEL,
+                              RequestAction::MAX);
+  } else if (blocked_request.new_url && !blocked_request.new_url->is_empty()) {
     request_time_tracker_->SetRequestRedirected(request_id);
+    UMA_HISTOGRAM_ENUMERATION(kWebRequestActionUMA, RequestAction::REDIRECT,
+                              RequestAction::MAX);
+  } else if (credentials_set) {
+    UMA_HISTOGRAM_ENUMERATION(kWebRequestActionUMA,
+                              RequestAction::SET_AUTH_CREDENTIALS,
+                              RequestAction::MAX);
   }
 
   // This triggers onErrorOccurred if canceled is true.
   int rv = canceled ? net::ERR_BLOCKED_BY_CLIENT : net::OK;
 
   if (!blocked_request.callback.is_null()) {
     net::CompletionCallback callback = blocked_request.callback;
     // Ensure that request is removed before callback because the callback
     // might trigger the next event.
     blocked_requests_.erase(request_id);
@@ skipping 522 matching lines @@
   // Since EventListeners are segmented by browser_context, check that
   // last, as it is exceedingly unlikely to be different.
   return extension_id == that.extension_id &&
          sub_event_name == that.sub_event_name &&
          web_view_instance_id == that.web_view_instance_id &&
          embedder_process_id == that.embedder_process_id &&
          browser_context == that.browser_context;
 }
 
 }  // namespace extensions