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

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 0746e713f20785915aada189dc328dcd5bdd1aa2..238ee399cb73807ec985727e720c096e41c2a1f5 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -56,7 +56,6 @@
 #include "content/child/child_histogram_message_filter.h"
 #include "content/child/child_resource_message_filter.h"
 #include "content/child/child_shared_bitmap_manager.h"
-#include "content/child/content_child_helpers.h"
 #include "content/child/db_message_filter.h"
 #include "content/child/indexed_db/indexed_db_dispatcher.h"
 #include "content/child/indexed_db/indexed_db_message_filter.h"
@@ -467,22 +466,6 @@ void StringToUintVector(const std::string& str, std::vector<unsigned>* vector) {
 
 }  // namespace
 
-// For measuring memory usage after each task. Behind a command line flag.
-class 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 {
-    LOCAL_HISTOGRAM_MEMORY_KB("Memory.RendererUsed", GetMemoryUsageKB());
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(MemoryObserver);
-};
-
 RenderThreadImpl::HistogramCustomizer::HistogramCustomizer() {
   custom_histograms_.insert("V8.MemoryExternalFragmentationTotal");
   custom_histograms_.insert("V8.MemoryHeapSampleTotalCommitted");
@@ -864,11 +847,6 @@ void RenderThreadImpl::Shutdown() {
   FOR_EACH_OBSERVER(
       RenderProcessObserver, observers_, OnRenderProcessShutdown());
 
-  if (memory_observer_) {
-    message_loop()->RemoveTaskObserver(memory_observer_.get());
-    memory_observer_.reset();
-  }
-
   // Wait for all databases to be closed.
   if (blink_platform_impl_) {
     // Crash the process if they fail to close after a generous amount of time.
@@ -1315,11 +1293,6 @@ void RenderThreadImpl::EnsureWebKitInitialized() {
   SkGraphics::SetImageGeneratorFromEncodedFactory(
       blink::WebImageGenerator::create);
 
-  if (command_line.HasSwitch(switches::kMemoryMetrics)) {
-    memory_observer_.reset(new MemoryObserver());
-    message_loop()->AddTaskObserver(memory_observer_.get());
-  }
-
   if (command_line.HasSwitch(switches::kExplicitlyAllowedPorts)) {
     std::string allowed_ports =
         command_line.GetSwitchValueASCII(switches::kExplicitlyAllowedPorts);