base: Use DiscardableMemoryManager on MacOSX.

base/memory/discardable_memory_manager.cc

Index: base/memory/discardable_memory_manager.cc
diff --git a/base/memory/discardable_memory_manager.cc b/base/memory/discardable_memory_manager.cc
index 6ede8a39cf8bbc54659468e7adb520103d2c7898..3e90d223a56076f2eeb1c406f117092f16c90e1a 100644
--- a/base/memory/discardable_memory_manager.cc
+++ b/base/memory/discardable_memory_manager.cc
@@ -12,22 +12,15 @@
 
 namespace base {
 namespace internal {
-namespace {
 
-// This is admittedly pretty magical. It's approximately enough memory for four
-// 2560x1600 images.
-static const size_t kDefaultMemoryLimit = 64 * 1024 * 1024;
-static const size_t kDefaultBytesToKeepUnderModeratePressure =
-    kDefaultMemoryLimit / 4;
-
-}  // namespace
-
-DiscardableMemoryManager::DiscardableMemoryManager()
+DiscardableMemoryManager::DiscardableMemoryManager(
+    size_t memory_limit,
+    size_t bytes_to_keep_under_moderate_pressure)
     : allocations_(AllocationMap::NO_AUTO_EVICT),
       bytes_allocated_(0),
-      memory_limit_(kDefaultMemoryLimit),
+      memory_limit_(memory_limit),
       bytes_to_keep_under_moderate_pressure_(
-          kDefaultBytesToKeepUnderModeratePressure) {
+          bytes_to_keep_under_moderate_pressure) {
   BytesAllocatedChanged();
 }