Add metric measuring Feature Provider Static() length in the browser process.

extensions/common/features/feature_provider.cc

 // Copyright 2013 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/common/features/feature_provider.h"
 
 #include <map>
 
 #include "base/basictypes.h"
+#include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/memory/linked_ptr.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/trace_event/trace_event.h"
+#include "content/public/common/content_switches.h"
 #include "extensions/common/extensions_client.h"
+#include "extensions/common/switches.h"
 
 namespace extensions {
 
 namespace {
 
 class Static {
  public:
   FeatureProvider* GetFeatures(const std::string& name) const {
     FeatureProviderMap::const_iterator it = feature_providers_.find(name);
     CHECK(it != feature_providers_.end());
     return it->second.get();
   }
 
  private:
   friend struct base::DefaultLazyInstanceTraits<Static>;
 
   Static() {
+    TRACE_EVENT0("startup", "extensions::FeatureProvider::Static");
+    base::Time begin_time = base::Time::Now();
+
     ExtensionsClient* client = ExtensionsClient::Get();
     feature_providers_["api"] =
         make_linked_ptr(client->CreateFeatureProvider("api").release());
     feature_providers_["manifest"] =
         make_linked_ptr(client->CreateFeatureProvider("manifest").release());
     feature_providers_["permission"] =
         make_linked_ptr(client->CreateFeatureProvider("permission").release());
     feature_providers_["behavior"] =
         make_linked_ptr(client->CreateFeatureProvider("behavior").release());
+
+    base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+    std::string process_type =
+        command_line->GetSwitchValueASCII(::switches::kProcessType);
+
+    // Measure time only for browser process. This method gets called by the
+    // browser process on startup, as well as on renderer and extension
+    // processes throughout the execution of the browser. We are more
+    // interested in how long this takes as a startup cost, so we are
+    // just measuring the time in the browser process.
+    if (process_type == "") {

[Ilya Sherman, 2015/03/13 22:25:18]

nit: It's generally better to use std::string() rather than "".  For example, if
somebody were to ever come along and change the type of process_type to also be
a char*, this comparison would fail.  That particular failure mode is unlikely,
I admit, but it's generally best not to rely on implicit conversions where
they're not needed.

[rkaplow, 2015/03/14 19:16:32]

Done.

+      UMA_HISTOGRAM_TIMES("Extensions.FeatureProviderStaticInitTime",
+                          base::Time::Now() - begin_time);
+    }
   }
 
   typedef std::map<std::string, linked_ptr<FeatureProvider> >
       FeatureProviderMap;
 
   FeatureProviderMap feature_providers_;
 };
 
 base::LazyInstance<Static> g_static = LAZY_INSTANCE_INITIALIZER;
 
@@ skipping 49 matching lines @@
 const Feature* FeatureProvider::GetPermissionFeature(const std::string& name) {
   return GetFeatureFromProviderByName("permission", name);
 }
 
 // static
 const Feature* FeatureProvider::GetBehaviorFeature(const std::string& name) {
   return GetFeatureFromProviderByName("behavior", name);
 }
 
 }  // namespace extensions