Add startup metrics that measure the performance of the first web contents.

chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h

Index: chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
diff --git a/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h b/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
index 91b904d77375f5a13d43d063a1b58a60ae874ed0..7d9eceb4be58e6ee869f450122b48229b7974dd3 100644
--- a/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
+++ b/chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.h
@@ -9,6 +9,7 @@
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/chrome_browser_main_extra_parts.h"
+#include "chrome/browser/metrics/first_web_contents_profiler.h"
 #include "ui/gfx/display_observer.h"
 
 class ChromeBrowserMainParts;
@@ -17,8 +18,10 @@ namespace chrome {
 void AddMetricsExtraParts(ChromeBrowserMainParts* main_parts);
 }
 
-class ChromeBrowserMainExtraPartsMetrics : public ChromeBrowserMainExtraParts,
-                                           public gfx::DisplayObserver {
+class ChromeBrowserMainExtraPartsMetrics
+    : public ChromeBrowserMainExtraParts,
+      public gfx::DisplayObserver,
+      public FirstWebContentsProfiler::Delegate {
  public:
   ChromeBrowserMainExtraPartsMetrics();
   ~ChromeBrowserMainExtraPartsMetrics() override;
@@ -40,6 +43,9 @@ class ChromeBrowserMainExtraPartsMetrics : public ChromeBrowserMainExtraParts,
   virtual void OnDisplayMetricsChanged(const gfx::Display& display,
                                        uint32_t changed_metrics) override;
 
+  // FirstWebContentsProfilerDelegate overrides.
+  void ProfilerFinishedCollectingMetrics() override;
+
   // If the number of displays has changed, emit a UMA metric.
   void EmitDisplaysChangedMetric();
 
@@ -50,6 +56,9 @@ class ChromeBrowserMainExtraPartsMetrics : public ChromeBrowserMainExtraParts,
   // screen.
   bool is_screen_observer_;
 
+  // Measures start up performance of the first active web contents.
+  scoped_ptr<FirstWebContentsProfiler> first_web_contents_profiler_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainExtraPartsMetrics);
 };