Purge memory before suspending timer queues when backgrounded.

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

Index: third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
index 1e7b4e5cd8fa786eacdb6d94ff2d9b5d25a534f4..53800cce915febc22afb64ff8269a0bf97c7c7e0 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
@@ -24,6 +24,7 @@
 #include "platform/scheduler/renderer/task_queue_throttler.h"
 #include "platform/scheduler/renderer/web_view_scheduler_impl.h"
 #include "platform/scheduler/renderer/webthread_impl_for_renderer_scheduler.h"
+#include "public/platform/Platform.h"
 
 namespace blink {
 namespace scheduler {
@@ -1574,6 +1575,7 @@ void RendererSchedulerImpl::SuspendTimerQueueWhenBackgrounded() {
 
   MainThreadOnly().timer_queue_suspended_when_backgrounded = true;
   ForceUpdatePolicy();
+  Platform::current()->requestPurgeMemory();
 }
 
 void RendererSchedulerImpl::ResumeTimerQueueWhenForegroundedOrResumed() {