Adds the UserInputMonitor implementation for Mac.

media/base/user_input_monitor.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/user_input_monitor.h"
 
 #include "third_party/skia/include/core/SkPoint.h"
 
 namespace media {
 
 #ifdef DISABLE_USER_INPUT_MONITOR
 scoped_ptr<UserInputMonitor> UserInputMonitor::Create(
     const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
     const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner) {
   return scoped_ptr<UserInputMonitor>();
 }
 #endif  // DISABLE_USER_INPUT_MONITOR
 
 UserInputMonitor::~UserInputMonitor() {
   DCHECK(!monitoring_mouse_);
-  DCHECK(!monitoring_keyboard_);
+  DCHECK(!key_press_counter_references_);
 }
 
 void UserInputMonitor::AddMouseListener(MouseEventListener* listener) {
   base::AutoLock auto_lock(lock_);
   mouse_listeners_.AddObserver(listener);
   if (!monitoring_mouse_) {
     StartMouseMonitoring();
     monitoring_mouse_ = true;
     DVLOG(2) << "Started mouse monitoring.";
   }
 }
+
 void UserInputMonitor::RemoveMouseListener(MouseEventListener* listener) {
   base::AutoLock auto_lock(lock_);
   mouse_listeners_.RemoveObserver(listener);
   if (mouse_listeners_.size() == 0) {
     StopMouseMonitoring();
     monitoring_mouse_ = false;
     DVLOG(2) << "Stopped mouse monitoring.";
   }
 }
-void UserInputMonitor::AddKeyStrokeListener(KeyStrokeListener* listener) {
+
+void UserInputMonitor::EnableKeyPressMonitoring() {
   base::AutoLock auto_lock(lock_);
-  key_stroke_listeners_.AddObserver(listener);
-  if (!monitoring_keyboard_) {
+  key_press_counter_references_++;

[DaleCurtis, 2013/08/23 02:16:22]

style perfers ++var or you can inline it in the if statement if you're so
inclined.

+  if (key_press_counter_references_ == 1) {
     StartKeyboardMonitoring();
-    monitoring_keyboard_ = true;
     DVLOG(2) << "Started keyboard monitoring.";
   }
 }
-void UserInputMonitor::RemoveKeyStrokeListener(KeyStrokeListener* listener) {
+
+void UserInputMonitor::DisableKeyPressMonitoring() {
   base::AutoLock auto_lock(lock_);
-  key_stroke_listeners_.RemoveObserver(listener);
-  if (key_stroke_listeners_.size() == 0) {
+  DCHECK(key_press_counter_references_ > 0);

[DaleCurtis, 2013/08/23 02:16:22]

DCHECK_GT

+  key_press_counter_references_--;

[DaleCurtis, 2013/08/23 02:16:22]

prefer --var ditto on inline if you want.

+  if (key_press_counter_references_ == 0) {
     StopKeyboardMonitoring();
-    monitoring_keyboard_ = false;
+    pressed_keys_.clear();
+    total_key_presses_ = 0;
     DVLOG(2) << "Stopped keyboard monitoring.";
   }
 }
 
+size_t UserInputMonitor::GetKeyPressCount() const {
+  base::AutoLock auto_lock(lock_);
+  DCHECK(key_press_counter_references_);
+  return total_key_presses_;
+}
+
 UserInputMonitor::UserInputMonitor()
-    : monitoring_mouse_(false), monitoring_keyboard_(false) {}
+    : monitoring_mouse_(false),
+      key_press_counter_references_(0),
+      total_key_presses_(0) {}
 
 void UserInputMonitor::OnMouseEvent(const SkIPoint& position) {
   base::AutoLock auto_lock(lock_);
+  if (!monitoring_mouse_)
+    return;
   FOR_EACH_OBSERVER(
       MouseEventListener, mouse_listeners_, OnMouseMoved(position));
 }
 
 void UserInputMonitor::OnKeyboardEvent(ui::EventType event,
                                        ui::KeyboardCode key_code) {
   base::AutoLock auto_lock(lock_);
-  // Updates the pressed keys and maybe notifies the key_stroke_listeners_.
+  if (!key_press_counter_references_)
+    return;
+  // Updates the pressed keys and the total count of key presses.
   if (event == ui::ET_KEY_PRESSED) {
     if (pressed_keys_.find(key_code) != pressed_keys_.end())
       return;
     pressed_keys_.insert(key_code);
-    DVLOG(6) << "Key stroke detected.";
-    FOR_EACH_OBSERVER(KeyStrokeListener, key_stroke_listeners_, OnKeyStroke());
+    total_key_presses_++;

[DaleCurtis, 2013/08/23 02:16:22]

Prefer ++var.

+    DVLOG(6) << "Key press detected, total count: " << total_key_presses_;
   } else {
     DCHECK_EQ(ui::ET_KEY_RELEASED, event);
     DCHECK(pressed_keys_.find(key_code) != pressed_keys_.end());
     pressed_keys_.erase(key_code);
   }
 }
 
 }  // namespace media