HostDiscardableSharedMemoryManager should store the default memory limit

content/common/host_discardable_shared_memory_manager.cc

Index: content/common/host_discardable_shared_memory_manager.cc
diff --git a/content/common/host_discardable_shared_memory_manager.cc b/content/common/host_discardable_shared_memory_manager.cc
index aafd5d6376f80eeacd788307ae51efe6fcaaafdf..e349fca4171c1a32a1daf1ef22f50913e1d7c89f 100644
--- a/content/common/host_discardable_shared_memory_manager.cc
+++ b/content/common/host_discardable_shared_memory_manager.cc
@@ -164,7 +164,8 @@ HostDiscardableSharedMemoryManager::MemorySegment::~MemorySegment() {
 }
 
 HostDiscardableSharedMemoryManager::HostDiscardableSharedMemoryManager()
-    : memory_limit_(GetDefaultMemoryLimit()),
+    : default_memory_limit_(GetDefaultMemoryLimit()),

[bashi, 2016/10/04 03:13:10]

Though GetDefaultMemoryLimit() could be dynamically changed, I think using the
initial value as a default value makes sense because (1) the implementation is
simpler and (2) amount of free disk space isn't a primary metric.

+      memory_limit_(default_memory_limit_),
       bytes_allocated_(0),
       memory_pressure_listener_(new base::MemoryPressureListener(
           base::Bind(&HostDiscardableSharedMemoryManager::OnMemoryPressure,
@@ -352,7 +353,7 @@ void HostDiscardableSharedMemoryManager::OnMemoryStateChange(
     base::MemoryState state) {
   switch (state) {
     case base::MemoryState::NORMAL:
-      SetMemoryLimit(GetDefaultMemoryLimit());
+      SetMemoryLimit(default_memory_limit_);
       break;
     case base::MemoryState::THROTTLED:
       SetMemoryLimit(0);