base: Add free list implementation to browser-wide discardable memory system.

base/memory/discardable_memory_shmem.h

Index: base/memory/discardable_memory_shmem.h
diff --git a/base/memory/discardable_memory_shmem.h b/base/memory/discardable_memory_shmem.h
index d25f84cb46dbdb364d1a86dbf4c9286c8759d02e..46bc5887ec00b8e70eba42f5c380afba40d121bc 100644
--- a/base/memory/discardable_memory_shmem.h
+++ b/base/memory/discardable_memory_shmem.h
@@ -10,7 +10,7 @@
 #include "base/memory/discardable_memory_manager.h"
 
 namespace base {
-class DiscardableSharedMemory;
+class DiscardableMemoryShmemChunk;
 
 namespace internal {
 
@@ -40,7 +40,7 @@ class DiscardableMemoryShmem
 
  private:
   const size_t bytes_;
-  scoped_ptr<DiscardableSharedMemory> shared_memory_;
+  scoped_ptr<DiscardableMemoryShmemChunk> chunk_;
   bool is_locked_;
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryShmem);