[tracing] Display the locked size of discardable memory segment.

content/common/discardable_shared_memory_heap.h

Index: content/common/discardable_shared_memory_heap.h
diff --git a/content/common/discardable_shared_memory_heap.h b/content/common/discardable_shared_memory_heap.h
index 100b03f169611388e16d601276913d119cca3f64..80bbccfb1a7ec660f796574463d7b8aaed542394 100644
--- a/content/common/discardable_shared_memory_heap.h
+++ b/content/common/discardable_shared_memory_heap.h
@@ -8,6 +8,7 @@
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/containers/linked_list.h"
+#include "base/memory/discardable_shared_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/trace_event/process_memory_dump.h"
@@ -27,20 +28,31 @@ class CONTENT_EXPORT DiscardableSharedMemoryHeap {
    public:
     ~Span();
 
-    base::DiscardableSharedMemory* shared_memory() { return shared_memory_; }
+    bool shared_memory() { return shared_memory_; }

[ssid, 2015/09/29 16:03:55]

I have also removed the getter here since it is no longer required, just added
isResident method

     size_t start() const { return start_; }
     size_t length() const { return length_; }
 
+    base::DiscardableSharedMemory::LockResult Lock(size_t page_size);
+    void Unlock(size_t page_size);

[reveman, 2015/09/29 22:58:31]

I'd like to keep Span class as a simple container without any real logic. Can we
instead add getter/setters for is_locked? and use them from the manager?

+
+    // Returns true if shared_memory segment is resident.
+    bool IsMemoryResident() const;
+
+    // Returns true if the span is locked by the client.
+    bool is_locked() { return is_locked_; }
+
    private:
     friend class DiscardableSharedMemoryHeap;
 
     Span(base::DiscardableSharedMemory* shared_memory,
          size_t start,
-         size_t length);
+         size_t length,
+         bool is_locked);
 
     base::DiscardableSharedMemory* shared_memory_;
     size_t start_;
     size_t length_;
+    bool is_locked_;
 
     DISALLOW_COPY_AND_ASSIGN(Span);
   };