Flash: Use better APIs for preventing sleep

chrome/browser/renderer_host/pepper/pepper_flash_browser_host.cc

Index: chrome/browser/renderer_host/pepper/pepper_flash_browser_host.cc
diff --git a/chrome/browser/renderer_host/pepper/pepper_flash_browser_host.cc b/chrome/browser/renderer_host/pepper/pepper_flash_browser_host.cc
index 5ce665036057c6062f7d54cc8bc8ad568c52e7a3..c8ff5919e21c1ae7b530ef85248e6fa82892e76a 100644
--- a/chrome/browser/renderer_host/pepper/pepper_flash_browser_host.cc
+++ b/chrome/browser/renderer_host/pepper/pepper_flash_browser_host.cc
@@ -13,6 +13,7 @@
 #include "content/public/browser/browser_ppapi_host.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_process_host.h"
+#include "device/power_save_blocker/power_save_blocker.h"
 #include "ipc/ipc_message_macros.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/private/ppb_flash.h"
@@ -80,19 +81,20 @@ int32_t PepperFlashBrowserHost::OnResourceMessageReceived(
 
 int32_t PepperFlashBrowserHost::OnUpdateActivity(
     ppapi::host::HostMessageContext* host_context) {
-#if defined(OS_WIN)
-  // Reading then writing back the same value to the screensaver timeout system
-  // setting resets the countdown which prevents the screensaver from turning
-  // on "for a while". As long as the plugin pings us with this message faster
-  // than the screensaver timeout, it won't go on.
-  int value = 0;
-  if (SystemParametersInfo(SPI_GETSCREENSAVETIMEOUT, 0, &value, 0))
-    SystemParametersInfo(SPI_SETSCREENSAVETIMEOUT, value, NULL, 0);
-#elif defined(OS_MACOSX)
-  UpdateSystemActivity(OverallAct);
-#else
-// TODO(brettw) implement this for other platforms.
-#endif
+  device::PowerSaveBlocker* blocker = new device::PowerSaveBlocker(
+      device::PowerSaveBlocker::kPowerSaveBlockPreventAppSuspension,
+      device::PowerSaveBlocker::kReasonOther, "Requested By PepperFlash",
+      BrowserThread::GetTaskRunnerForThread(BrowserThread::UI),
+      BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE));
+  auto delete_blocker = [](device::PowerSaveBlocker* blocker) {
+    delete blocker;
+  };
+  // There is no specification for how long OnUpdateActivity should prevent the
+  // screen from going to sleep. Empirically, twitch.tv calls this method every
+  // 10 seconds. Be conservative and allow 45 seconds before deleting the block.
+  BrowserThread::PostDelayedTask(BrowserThread::IO, FROM_HERE,
+                                 base::Bind(delete_blocker, blocker),
+                                 base::TimeDelta::FromSeconds(45));

[bbudge, 2016/10/13 19:53:51]

Since this is a plugin API, it seems bad to allow the plugin to create an
unlimited number of PowerSaveBlocker instances.

Could you instead hold a reference to the PowerSaveBlocker on this host class,
and post tasks to reset that reference? You'd have to check in UpdateActivity
for a pending task and kill that before launching another.

[ccameron, 2016/10/14 21:39:43]

Sure -- switched it to a DelayTimer impl.

   return PP_OK;
 }