perf: use flat_set, flat_map for small, trivially-moved containers (#40817)

* refactor: use base::flat_map in ElectronMenuModel

* refactor: use base::flat_map in BuildSubmenuFromModel()

* refactor: use base::flat_map in GetDialogsMap()

* refactor: use base::flat_map in DesktopCapturer

* refactor: use base::flat_map, flat_set in ElectronBrowserClient

* refactor: use base::flat_map in ProxyingURLLoaderFactory

* refactor: use base::flat_map in MapToCommonId()

* refactor: use base::flat_map for g_map_id

* refactor: use base::flat_map for ViewsDelegate::AppbarAutohideEdgeMap

* refactor: use base::flat_map for App::app_metrics_

* refactor: use base::flat_map for PowerSaveBlocker::wake_lock_types_

* refactor: use base::flat_map for NativeImage::hicons_

* refactor: use base::flat_map for MenuViews::menu_runners_

* refactor: use base::flat_map for WebViewManager::web_contents_embedder_map_

* refactor: use base::flat_map for InspectableWebContents::extensions_api_

* refactor: use base::flat_set for libnotify GetServerCapabilities()

* refactor: use base::flat_set for InspectableWebContents::loaders_

* refactor: use base::flat_set for ElectronRendererClient::environments_

refactor: use base::flat_set for ElectronRendererClient::injected_frames_

* refactor: use base::flat_set for WebWorkerObserver::environments_

shell/browser/api/electron_api_app.h

@@ -5,11 +5,11 @@
 #ifndef ELECTRON_SHELL_BROWSER_API_ELECTRON_API_APP_H_
 #define ELECTRON_SHELL_BROWSER_API_ELECTRON_API_APP_H_
 
-#include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
+#include "base/containers/flat_map.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "chrome/browser/icon_manager.h"
 #include "chrome/browser/process_singleton.h"
@@ -259,9 +259,8 @@ class App : public ElectronBrowserClient::Delegate,
 
   base::FilePath app_path_;
 
-  using ProcessMetricMap =
-      std::map<int, std::unique_ptr<electron::ProcessMetric>>;
-  ProcessMetricMap app_metrics_;
+  // pid -> electron::ProcessMetric
+  base::flat_map<int, std::unique_ptr<electron::ProcessMetric>> app_metrics_;
 
   bool disable_hw_acceleration_ = false;
   bool disable_domain_blocking_for_3DAPIs_ = false;

shell/browser/api/electron_api_desktop_capturer.cc

@@ -4,11 +4,11 @@
 
 #include "shell/browser/api/electron_api_desktop_capturer.h"
 
-#include <map>
 #include <memory>
 #include <utility>
 #include <vector>
 
+#include "base/containers/flat_map.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
@@ -42,11 +42,11 @@
 
 #if BUILDFLAG(IS_LINUX)
 // Private function in ui/base/x/x11_display_util.cc
-std::map<x11::RandR::Output, int> GetMonitors(
+base::flat_map<x11::RandR::Output, int> GetMonitors(
     std::pair<uint32_t, uint32_t> version,
     x11::RandR* randr,
     x11::Window window) {
-  std::map<x11::RandR::Output, int> output_to_monitor;
+  base::flat_map<x11::RandR::Output, int> output_to_monitor;
   if (version >= std::pair<uint32_t, uint32_t>{1, 5}) {
     if (auto reply = randr->GetMonitors({window}).Sync()) {
       for (size_t monitor = 0; monitor < reply->monitors.size(); monitor++) {
@@ -76,12 +76,12 @@ std::vector<uint8_t> GetEDIDProperty(x11::RandR* randr,
 // Find the mapping from monitor name atom to the display identifier
 // that the screen API uses. Based on the logic in BuildDisplaysFromXRandRInfo
 // in ui/base/x/x11_display_util.cc
-std::map<int32_t, uint32_t> MonitorAtomIdToDisplayId() {
+base::flat_map<int32_t, uint32_t> MonitorAtomIdToDisplayId() {
   auto* connection = x11::Connection::Get();
   auto& randr = connection->randr();
   auto x_root_window = ui::GetX11RootWindow();
 
-  std::map<int32_t, uint32_t> monitor_atom_to_display;
+  base::flat_map<int32_t, uint32_t> monitor_atom_to_display;
 
   auto resources = randr.GetScreenResourcesCurrent({x_root_window}).Sync();
   if (!resources) {
@@ -89,7 +89,7 @@ std::map<int32_t, uint32_t> MonitorAtomIdToDisplayId() {
     return monitor_atom_to_display;
   }
 
-  std::map<x11::RandR::Output, int> output_to_monitor =
+  const auto output_to_monitor =
       GetMonitors(connection->randr_version(), &randr, x_root_window);
   auto monitors_reply = randr.GetMonitors({x_root_window}).Sync();
 
@@ -385,8 +385,7 @@ void DesktopCapturer::UpdateSourcesList(DesktopMediaList* list) {
     // display name atom and the display id is either the EDID or the
     // loop index when that display was found (see
     // BuildDisplaysFromXRandRInfo in ui/base/x/x11_display_util.cc)
-    std::map<int32_t, uint32_t> monitor_atom_to_display_id =
-        MonitorAtomIdToDisplayId();
+    const auto monitor_atom_to_display_id = MonitorAtomIdToDisplayId();
     for (auto& source : screen_sources) {
       auto display_id_iter =
           monitor_atom_to_display_id.find(source.media_list_source.id.id);

shell/browser/api/electron_api_menu_views.cc

@@ -52,24 +52,26 @@ void MenuViews::PopupAt(BaseWindow* window,
   auto close_callback = base::AdaptCallbackForRepeating(
       base::BindOnce(&MenuViews::OnClosed, weak_factory_.GetWeakPtr(),
                      window_id, std::move(callback_with_ref)));
-  menu_runners_[window_id] =
+  auto& runner = menu_runners_[window_id] =
       std::make_unique<MenuRunner>(model(), flags, std::move(close_callback));
-  menu_runners_[window_id]->RunMenuAt(
-      native_window->widget(), nullptr, gfx::Rect(location, gfx::Size()),
-      views::MenuAnchorPosition::kTopLeft, source_type);
+  runner->RunMenuAt(native_window->widget(), nullptr,
+                    gfx::Rect{location, gfx::Size{}},
+                    views::MenuAnchorPosition::kTopLeft, source_type);
 }
 
 void MenuViews::ClosePopupAt(int32_t window_id) {
-  auto runner = menu_runners_.find(window_id);
-  if (runner != menu_runners_.end()) {
+  if (auto iter = menu_runners_.find(window_id); iter != menu_runners_.end()) {
     // Close the runner for the window.
-    runner->second->Cancel();
-  } else if (window_id == -1) {
-    // Or just close all opened runners.
-    for (auto it = menu_runners_.begin(); it != menu_runners_.end();) {
-      // The iterator is invalidated after the call.
-      (it++)->second->Cancel();
-    }
+    iter->second->Cancel();
+    return;
+  }
+
+  if (window_id == -1) {
+    // When -1 is passed in, close all opened runners.
+    // Note: `Cancel()` invalidaes iters, so move() to a temp before looping
+    auto tmp = std::move(menu_runners_);
+    for (auto& [id, runner] : tmp)
+      runner->Cancel();
   }
 }
 

shell/browser/api/electron_api_menu_views.h

@@ -5,9 +5,9 @@
 #ifndef ELECTRON_SHELL_BROWSER_API_ELECTRON_API_MENU_VIEWS_H_
 #define ELECTRON_SHELL_BROWSER_API_ELECTRON_API_MENU_VIEWS_H_
 
-#include <map>
 #include <memory>
 
+#include "base/containers/flat_map.h"
 #include "base/memory/weak_ptr.h"
 #include "shell/browser/api/electron_api_menu.h"
 #include "ui/display/screen.h"
@@ -33,7 +33,7 @@ class MenuViews : public Menu {
   void OnClosed(int32_t window_id, base::OnceClosure callback);
 
   // window ID -> open context menu
-  std::map<int32_t, std::unique_ptr<views::MenuRunner>> menu_runners_;
+  base::flat_map<int32_t, std::unique_ptr<views::MenuRunner>> menu_runners_;
 
   base::WeakPtrFactory<MenuViews> weak_factory_{this};
 };

shell/browser/api/electron_api_power_save_blocker.h

@@ -5,8 +5,7 @@
 #ifndef ELECTRON_SHELL_BROWSER_API_ELECTRON_API_POWER_SAVE_BLOCKER_H_
 #define ELECTRON_SHELL_BROWSER_API_ELECTRON_API_POWER_SAVE_BLOCKER_H_
 
-#include <map>
-
+#include "base/containers/flat_map.h"
 #include "gin/handle.h"
 #include "gin/object_template_builder.h"
 #include "gin/wrappable.h"
@@ -48,8 +47,7 @@ class PowerSaveBlocker : public gin::Wrappable<PowerSaveBlocker> {
   bool is_wake_lock_active_ = false;
 
   // Map from id to the corresponding blocker type for each request.
-  using WakeLockTypeMap = std::map<int, device::mojom::WakeLockType>;
-  WakeLockTypeMap wake_lock_types_;
+  base::flat_map<int, device::mojom::WakeLockType> wake_lock_types_;
 
   mojo::Remote<device::mojom::WakeLock> wake_lock_;
 };

shell/browser/api/electron_api_system_preferences_mac.mm

@@ -4,7 +4,6 @@
 
 #include "shell/browser/api/electron_api_system_preferences.h"
 
-#include <map>
 #include <string>
 #include <utility>
 
@@ -14,6 +13,7 @@
 #import <Security/Security.h>
 
 #include "base/apple/scoped_cftyperef.h"
+#include "base/containers/flat_map.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/task/sequenced_task_runner.h"
@@ -81,7 +81,7 @@ namespace {
 int g_next_id = 0;
 
 // The map to convert |id| to |int|.
-std::map<int, id> g_id_map;
+base::flat_map<int, id> g_id_map;
 
 AVMediaType ParseMediaType(const std::string& media_type) {
   if (media_type == "camera") {