Kill --memory-metrics and on-demand Memory.Browser/RenderUsed histograms

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 22c3e582f82b06dc0d1d2f72e5baf507e15ce85e..751bb30d5beffc521106c2a3658e2169ab109bdb 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -378,27 +378,6 @@ base::win::MemoryPressureMonitor* CreateWinMemoryPressureMonitor(
 // The currently-running BrowserMainLoop.  There can be one or zero.
 BrowserMainLoop* g_current_browser_main_loop = NULL;
 
-// For measuring memory usage after each task. Behind a command line flag.
-class BrowserMainLoop::MemoryObserver : public base::MessageLoop::TaskObserver {
- public:
-  MemoryObserver() {}
-  ~MemoryObserver() override {}
-
-  void WillProcessTask(const base::PendingTask& pending_task) override {}
-
-  void DidProcessTask(const base::PendingTask& pending_task) override {
-#if !defined(OS_IOS)  // No ProcessMetrics on IOS.
-    scoped_ptr<base::ProcessMetrics> process_metrics(
-        base::ProcessMetrics::CreateCurrentProcessMetrics());
-    size_t private_bytes;
-    process_metrics->GetMemoryBytes(&private_bytes, NULL);
-    LOCAL_HISTOGRAM_MEMORY_KB("Memory.BrowserUsed", private_bytes >> 10);
-#endif
-  }
- private:
-  DISALLOW_COPY_AND_ASSIGN(MemoryObserver);
-};
-
 
 // BrowserMainLoop construction / destruction =============================
 
@@ -675,12 +654,6 @@ void BrowserMainLoop::PostMainMessageLoopStart() {
       ui::OzonePlatform::GetInstance()->OpenClientNativePixmapDevice());
 #endif
 
-  if (parsed_command_line_.HasSwitch(switches::kMemoryMetrics)) {
-    TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:MemoryObserver");
-    memory_observer_.reset(new MemoryObserver());
-    base::MessageLoop::current()->AddTaskObserver(memory_observer_.get());
-  }
-
   if (parsed_command_line_.HasSwitch(
           switches::kEnableAggressiveDOMStorageFlushing)) {
     TRACE_EVENT0("startup",