[Not for review] Discardable memory emulation

webkit/glue/web_discardable_memory_impl.cc

Index: webkit/glue/web_discardable_memory_impl.cc
diff --git a/webkit/glue/web_discardable_memory_impl.cc b/webkit/glue/web_discardable_memory_impl.cc
index d4c3ee280a86a68439761e10e6ae428a2dfd84d1..02f9458fbb51086587a2e4c57c75747e61b7cabf 100644
--- a/webkit/glue/web_discardable_memory_impl.cc
+++ b/webkit/glue/web_discardable_memory_impl.cc
@@ -6,17 +6,24 @@
 
 namespace webkit_glue {
 
-WebDiscardableMemoryImpl::WebDiscardableMemoryImpl()
-    : discardable_(new base::DiscardableMemory()) {
+WebDiscardableMemoryImpl::WebDiscardableMemoryImpl() {
+  if (base::DiscardableMemoryProvider* provider =
+      base::DiscardableMemoryProvider::GetInstance())
+    discardable_.reset(provider->CreateDiscardableMemory());
 }
 
 WebDiscardableMemoryImpl::~WebDiscardableMemoryImpl() {}
 
 bool WebDiscardableMemoryImpl::InitializeAndLock(size_t size) {
+  if (!discardable_)
+    return false;
   return discardable_->InitializeAndLock(size);
 }
 
 bool WebDiscardableMemoryImpl::lock() {
+  if (!discardable_)
+    return false;
+
   base::LockDiscardableMemoryStatus status = discardable_->Lock();
   switch (status) {
     case base::DISCARDABLE_MEMORY_SUCCESS:
@@ -31,10 +38,14 @@ bool WebDiscardableMemoryImpl::lock() {
 }
 
 void* WebDiscardableMemoryImpl::data() {
+  if (!discardable_)
+    return NULL;
   return discardable_->Memory();
 }
 
 void WebDiscardableMemoryImpl::unlock() {
+  if (!discardable_)
+    return;
   discardable_->Unlock();
 }