[Extensions] Short-circuit activity logging if not enabled

extensions/browser/api_activity_monitor.cc

Index: extensions/browser/api_activity_monitor.cc
diff --git a/extensions/browser/api_activity_monitor.cc b/extensions/browser/api_activity_monitor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7c5cf87afa6ca3bfbe8ba5192876dbf361ef8270
--- /dev/null
+++ b/extensions/browser/api_activity_monitor.cc
@@ -0,0 +1,74 @@
+// Copyright 2016 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_activity_monitor.h"
+
+#include "base/values.h"
+
+namespace extensions {
+namespace activity_monitor {
+
+namespace {
+
+Monitor g_event_monitor = nullptr;
+Monitor g_function_monitor = nullptr;
+WebRequestMonitor g_web_request_monitor = nullptr;
+
+}  // namespace
+
+Monitor GetApiEventMonitor() {
+  return g_event_monitor;
+}
+
+Monitor GetApiFunctionMonitor() {
+  return g_function_monitor;
+}
+
+WebRequestMonitor GetWebRequestMonitor() {
+  return g_web_request_monitor;
+}
+
+void SetApiEventMonitor(Monitor event_monitor) {
+  g_event_monitor = event_monitor;
+}
+
+void SetApiFunctionMonitor(Monitor function_monitor) {
+  g_function_monitor = function_monitor;
+}
+
+void SetWebRequestMonitor(WebRequestMonitor web_request_monitor) {
+  g_web_request_monitor = web_request_monitor;
+}
+
+void OnApiEventDispatched(content::BrowserContext* browser_context,
+                          const std::string& extension_id,
+                          const std::string& event_name,
+                          const base::ListValue& event_args) {
+  if (g_event_monitor)
+    g_event_monitor(browser_context, extension_id, event_name, event_args);
+}
+
+// Called when an extension calls an API function.
+void OnApiFunctionCalled(content::BrowserContext* browser_context,
+                         const std::string& extension_id,
+                         const std::string& api_name,
+                         const base::ListValue& args) {
+  if (g_function_monitor)
+    g_function_monitor(browser_context, extension_id, api_name, args);
+}
+
+void OnWebRequestApiUsed(content::BrowserContext* browser_context,
+                         const std::string& extension_id,
+                         const GURL& url,
+                         bool is_incognito,
+                         const std::string& api_call,
+                         std::unique_ptr<base::DictionaryValue> details) {
+  if (g_web_request_monitor) {
+    g_web_request_monitor(browser_context, extension_id, url, is_incognito,
+                          api_call, std::move(details));
+  }
+}
+
+}  // namespace activity_monitor
+}  // namespace extensions