base: Add NOTREACHED() for when using a non-supported discardable memory type.

base/memory/discardable_memory_linux.cc

Index: base/memory/discardable_memory_linux.cc
diff --git a/base/memory/discardable_memory_linux.cc b/base/memory/discardable_memory_linux.cc
index 578b2c1c756049559e902300dffe1ddf51a82635..d2cd6a542ab324007a2401be087e830e060779a1 100644
--- a/base/memory/discardable_memory_linux.cc
+++ b/base/memory/discardable_memory_linux.cc
@@ -29,10 +29,6 @@ void DiscardableMemory::GetSupportedTypes(
 scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemoryWithType(
     DiscardableMemoryType type, size_t size) {
   switch (type) {
-    case DISCARDABLE_MEMORY_TYPE_NONE:
-    case DISCARDABLE_MEMORY_TYPE_ASHMEM:
-    case DISCARDABLE_MEMORY_TYPE_MAC:
-      return scoped_ptr<DiscardableMemory>();
     case DISCARDABLE_MEMORY_TYPE_EMULATED: {
       scoped_ptr<internal::DiscardableMemoryEmulated> memory(
           new internal::DiscardableMemoryEmulated(size));
@@ -49,6 +45,11 @@ scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemoryWithType(
 
       return memory.PassAs<DiscardableMemory>();
     }
+    case DISCARDABLE_MEMORY_TYPE_NONE:
+    case DISCARDABLE_MEMORY_TYPE_ASHMEM:
+    case DISCARDABLE_MEMORY_TYPE_MAC:
+      NOTREACHED();
+      return scoped_ptr<DiscardableMemory>();
   }
 
   NOTREACHED();