Purge memory before suspending timer queues when backgrounded.

third_party/WebKit/public/platform/Platform.h

Index: third_party/WebKit/public/platform/Platform.h
diff --git a/third_party/WebKit/public/platform/Platform.h b/third_party/WebKit/public/platform/Platform.h
index 5835825aaaabaf8c720e15860bf1ffbb7764114c..d7d3e5c8da3609cda3e662c799d9f0f543848564 100644
--- a/third_party/WebKit/public/platform/Platform.h
+++ b/third_party/WebKit/public/platform/Platform.h
@@ -669,6 +669,12 @@ class BLINK_PLATFORM_EXPORT Platform {
 
   virtual WebTrialTokenValidator* trialTokenValidator() { return nullptr; }
 
+  // Memory ------------------------------------------------------------
+
+  // Requests purging memory. The platform may or may not purge memory,
+  // depending on memory pressure.
+  virtual void requestPurgeMemory() {}
+
  protected:
   Platform();
   virtual ~Platform() {}