Global Media Controls: Don't handle media keys on lock screen

This CL adds a check to prevent handling media keys when the screen is
locked.

Bug: 951485
Change-Id: I1a2481894e20ceee1879d32066cf969a0b4263bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1562370Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649654}

content/browser/media/media_keys_listener_manager_impl.cc

@@ -11,6 +11,7 @@
 #include "content/browser/browser_main_loop.h"
 #include "content/browser/media/hardware_key_media_controller.h"
 #include "ui/base/accelerators/accelerator.h"
+#include "ui/base/idle/idle.h"
 #include "ui/base/mpris/buildflags/buildflags.h"
 
 #if BUILDFLAG(USE_MPRIS)
@@ -128,6 +129,16 @@ void MediaKeysListenerManagerImpl::OnMediaKeysAccelerator(
   // We should never receive an accelerator that was never registered.
   DCHECK(delegate_map_.contains(accelerator.key_code()));
 
+#if defined(OS_WIN) || defined(OS_MACOSX)
+  // For privacy, we don't want to handle media keys when the system is locked.
+  // On Windows and Mac OS X, this will happen unless we explicitly prevent it.
+  // TODO(steimel): Consider adding an idle monitor instead and disabling the
+  // RemoteCommandCenter/SystemMediaTransportControls on lock so that other OS
+  // apps can take control.
+  if (ui::CheckIdleStateIsLocked())
+    return;
+#endif
+
   ListeningData* listening_data = delegate_map_[accelerator.key_code()].get();
 
   // If the HardwareKeyMediaController is listening and is allowed to listen,
@@ -152,6 +163,10 @@ void MediaKeysListenerManagerImpl::EnsureAuxiliaryServices() {
 #endif
 
 #if defined(OS_MACOSX)
+  // On Mac OS, we need to initialize the idle monitor in order to check if the
+  // system is locked.
+  ui::InitIdleMonitor();
+
   // Only create the NowPlayingInfoCenterNotifier if we're able to get a
   // NowPlayingInfoCenterDelegate.
   auto now_playing_info_center_delegate =