[Extensions] Add metrics for API binding generation time

extensions/renderer/module_system.cc

 // 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.
 
 #include "extensions/renderer/module_system.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
+#include "base/timer/elapsed_timer.h"
 #include "base/trace_event/trace_event.h"
 #include "content/public/renderer/render_frame.h"
 #include "content/public/renderer/render_view.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extensions_client.h"
 #include "extensions/renderer/console.h"
 #include "extensions/renderer/safe_builtins.h"
 #include "extensions/renderer/script_context.h"
 #include "extensions/renderer/script_context_set.h"
 #include "extensions/renderer/v8_helpers.h"
@@ skipping 349 matching lines @@
     v8::Local<v8::Name> property,
     const v8::PropertyCallbackInfo<v8::Value>& info) {
   LazyFieldGetterInner(property.As<v8::String>(), info, &ModuleSystem::Require);
 }
 
 // static
 void ModuleSystem::LazyFieldGetterInner(
     v8::Local<v8::String> property,
     const v8::PropertyCallbackInfo<v8::Value>& info,
     RequireFunction require_function) {
+  base::ElapsedTimer timer;
   CHECK(!info.Data().IsEmpty());
   CHECK(info.Data()->IsObject());
   v8::Isolate* isolate = info.GetIsolate();
   v8::HandleScope handle_scope(isolate);
   v8::Local<v8::Object> parameters = v8::Local<v8::Object>::Cast(info.Data());
   // This context should be the same as context()->v8_context().
   v8::Local<v8::Context> context = parameters->CreationContext();
   v8::Local<v8::Object> global(context->Global());
   v8::Local<v8::Value> module_system_value;
   if (!GetPrivate(context, global, kModuleSystem, &module_system_value) ||
@@ skipping 61 matching lines @@
   // returned every time a certain API is accessed.
   v8::Local<v8::Value> val = info.This();
   if (val->IsObject()) {
     v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(val);
     object->Delete(context, property);
     SetProperty(context, object, property, new_field);
   } else {
     NOTREACHED();
   }
   info.GetReturnValue().Set(new_field);
+
+  UMA_HISTOGRAM_TIMES("Extensions.ApiBindingGenerationTime", timer.Elapsed());
 }
 
 void ModuleSystem::SetLazyField(v8::Local<v8::Object> object,
                                 const std::string& field,
                                 const std::string& module_name,
                                 const std::string& module_field) {
   SetLazyField(
       object, field, module_name, module_field, &ModuleSystem::LazyFieldGetter);
 }
 
@@ skipping 278 matching lines @@
 
 void ModuleSystem::ClobberExistingNativeHandler(const std::string& name) {
   NativeHandlerMap::iterator existing_handler = native_handler_map_.find(name);
   if (existing_handler != native_handler_map_.end()) {
     clobbered_native_handlers_.push_back(std::move(existing_handler->second));
     native_handler_map_.erase(existing_handler);
   }
 }
 
 }  // namespace extensions