Revert "history: adds minimal memory dump information for history"

This reverts commit 04cab8f6.

Reason for revert: The data logged here shows we are very likely not creating a bunch of HistoryAddPageArgs that aren't getting written. The highest count created was 3 (the majority are 0), which implies this isn't an issue. See bug for more details.

Original change's description:
> history: adds minimal memory dump information for history
> 
> Before I add more exhaustive information I want to make sure I'm on the right
> track. This adds the count of the number of outstanding requests to add a
> page (url and other information) that haven't been processed yet.
> 
> BUG=807009
> TEST=none
> 
> Change-Id: Ieb18fe74e9e91fe4f99eb1a791b04367c60cfd0d
> Reviewed-on: https://chromium-review.googlesource.com/1234240
> Commit-Queue: Scott Violet <sky@chromium.org>
> Reviewed-by: Erik Chen <erikchen@chromium.org>
> Reviewed-by: Siddhartha S <ssid@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#592916}

TBR=sky@chromium.org,erikchen@chromium.org,ssid@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 807009
Change-Id: Ic0c01697bced51123b71f059905d98f9945eaa2f
Reviewed-on: https://chromium-review.googlesource.com/c/1276945Reviewed-by: Siddhartha S <ssid@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599209}

base/trace_event/memory_infra_background_whitelist.cc

@@ -35,7 +35,6 @@ const char* const kDumpProviderWhitelist[] = {
     "gpu::TextureManager",
     "FontCaches",
     "HistoryReport",
-    "HistoryService",
     "IPCChannel",
     "IndexedDBBackingStore",
     "InMemoryURLIndex",
@@ -99,7 +98,6 @@ const char* const kAllocatorDumpNameWhitelist[] = {
     "gpu/gl/renderbuffers/context_group_0x?",
     "gpu/gl/textures/context_group_0x?",
     "history/delta_file_service/leveldb_0x?",
-    "history/history_service",
     "history/usage_reports_buffer/leveldb_0x?",
     "java_heap",
     "java_heap/allocated_objects",

components/history/core/browser/history_service.cc

@@ -27,16 +27,12 @@
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram_macros.h"
-#include "base/no_destructor.h"
 #include "base/single_thread_task_runner.h"
-#include "base/synchronization/lock.h"
 #include "base/task/post_task.h"
 #include "base/task_runner_util.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
-#include "base/trace_event/memory_dump_manager.h"
-#include "base/trace_event/memory_dump_provider.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "components/history/core/browser/download_row.h"
@@ -103,92 +99,6 @@ void ExpireWebHistoryComplete(bool success) {
   // until this completes.
 }
 
-// Used for debugging 807009. This keeps a static of the number of instances of
-// AddPageMemoryDebuggingTask that have been created but not destroyed. This
-// count corresponds to the number of calls to AddPage() that have not yet been
-// processed by the HistoryBackend.
-class AddPageMemoryDebuggingTask {
- public:
-  // |real_task| is the task to actually call to HistoryBackend.
-  explicit AddPageMemoryDebuggingTask(base::OnceClosure real_task)
-      : real_task_(std::move(real_task)) {
-    base::AutoLock auto_lock(GetLock());
-    ++live_count_;
-  }
-
-  ~AddPageMemoryDebuggingTask() {
-    base::AutoLock auto_lock(GetLock());
-    DCHECK_GT(live_count_, 0);
-    --live_count_;
-  }
-
-  // Called on the background/db-thread to run the closure supplied to the
-  // constructor. The instance is deleted right after this call.
-  void RunOnDbThread() { std::move(real_task_).Run(); }
-
-  static int live_count() {
-    base::AutoLock auto_lock(GetLock());
-    return live_count_;
-  }
-
- private:
-  static base::Lock& GetLock() {
-    static base::NoDestructor<base::Lock> lock;
-    return *lock;
-  }
-
-  // The number of instances waiting to run.
-  static int live_count_;  // Guarded by getLock()
-
-  base::OnceClosure real_task_;
-
-  DISALLOW_COPY_AND_ASSIGN(AddPageMemoryDebuggingTask);
-};
-
-// static
-int AddPageMemoryDebuggingTask::live_count_ = 0;
-
-class HistoryMemoryDumpProvider : public base::trace_event::MemoryDumpProvider {
- public:
-  static HistoryMemoryDumpProvider* Get() {
-    if (!instance_)
-      instance_ = new HistoryMemoryDumpProvider();
-    return instance_;
-  }
-
-  // base::trace_event::MemoryDumpProvider:
-  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
-                    base::trace_event::ProcessMemoryDump* pmd) override {
-    // NOTE: this may be called on any thread, see constructor.
-    base::trace_event::MemoryAllocatorDump* dump =
-        pmd->CreateAllocatorDump("history/history_service");
-    dump->AddScalar("pending_add_pages",
-                    base::trace_event::MemoryAllocatorDump::kUnitsObjects,
-                    AddPageMemoryDebuggingTask::live_count());
-    return true;
-  }
-
- private:
-  HistoryMemoryDumpProvider() {
-    // NOTE: the nullptr arg means OnMemoryDump() may be called from any
-    // thread.
-    base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
-        this, "HistoryService", nullptr);
-  }
-
-  ~HistoryMemoryDumpProvider() override {
-    base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
-        this);
-  }
-
-  static HistoryMemoryDumpProvider* instance_;
-
-  DISALLOW_COPY_AND_ASSIGN(HistoryMemoryDumpProvider);
-};
-
-// static
-HistoryMemoryDumpProvider* HistoryMemoryDumpProvider::instance_ = nullptr;
-
 }  // namespace
 
 // Sends messages from the backend to us on the main thread. This must be a
@@ -288,10 +198,7 @@ HistoryService::HistoryService(std::unique_ptr<HistoryClient> history_client,
       history_client_(std::move(history_client)),
       visit_delegate_(std::move(visit_delegate)),
       backend_loaded_(false),
-      weak_ptr_factory_(this) {
-  // Make sure the HistoryMemoryDumpProvider is created and registered.
-  HistoryMemoryDumpProvider::Get();
-}
+      weak_ptr_factory_(this) {}
 
 HistoryService::~HistoryService() {
   DCHECK(thread_checker_.CalledOnValidThread());
@@ -502,13 +409,9 @@ void HistoryService::AddPage(const HistoryAddPageArgs& add_page_args) {
     }
   }
 
-  auto real_task =
-      base::BindOnce(&HistoryBackend::AddPage, history_backend_, add_page_args);
-  std::unique_ptr<AddPageMemoryDebuggingTask> debug_task =
-      std::make_unique<AddPageMemoryDebuggingTask>(std::move(real_task));
   ScheduleTask(PRIORITY_NORMAL,
-               base::BindOnce(&AddPageMemoryDebuggingTask::RunOnDbThread,
-                              std::move(debug_task)));
+               base::BindOnce(&HistoryBackend::AddPage, history_backend_,
+                              add_page_args));
 }
 
 void HistoryService::AddPageNoVisitForBookmark(const GURL& url,