Replace blink::WebDiscardableMemory with base::DiscardableMemory.

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index ab31fe7a32091683a9298c9a9df41e4c22e1018b..d401f967330e1b2e3b77471a2cb8e54c7cbda2c5 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -50,7 +50,6 @@
 #include "content/child/push_messaging/push_dispatcher.h"
 #include "content/child/push_messaging/push_provider.h"
 #include "content/child/thread_safe_sender.h"
-#include "content/child/web_discardable_memory_impl.h"
 #include "content/child/web_url_loader_impl.h"
 #include "content/child/web_url_request_util.h"
 #include "content/child/websocket_bridge.h"
@@ -976,11 +975,6 @@ size_t BlinkPlatformImpl::numberOfProcessors() {
   return static_cast<size_t>(base::SysInfo::NumberOfProcessors());
 }
 
-blink::WebDiscardableMemory*
-BlinkPlatformImpl::allocateAndLockDiscardableMemory(size_t bytes) {
-  return content::WebDiscardableMemoryImpl::CreateLockedMemory(bytes).release();
-}
-
 size_t BlinkPlatformImpl::maxDecodedImageBytes() {
 #if defined(OS_ANDROID)
   if (base::SysInfo::IsLowEndDevice()) {