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

content/common/discardable_shared_memory_heap.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_
 #define CONTENT_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_
 
 #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"
 #include "content/common/content_export.h"
 
 namespace base {
 class DiscardableSharedMemory;
 }
 
 namespace content {
 
 // Implements a heap of discardable shared memory. An array of free lists
 // is used to keep track of free blocks.
 class CONTENT_EXPORT DiscardableSharedMemoryHeap {
  public:
   class CONTENT_EXPORT Span : public base::LinkNode<Span> {
    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);
   };
 
   explicit DiscardableSharedMemoryHeap(size_t block_size);
   ~DiscardableSharedMemoryHeap();
 
   // Grow heap using |shared_memory| and return a span for this new memory.
   // |shared_memory| must be aligned to the block size and |size| must be a
   // multiple of the block size. |deleted_callback| is called when
@@ skipping 114 matching lines @@
   // is a free list of runs that consist of k blocks. The 256th entry is a
   // free list of runs that have length >= 256 blocks.
   base::LinkedList<Span> free_spans_[256];
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableSharedMemoryHeap);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_DISCARDABLE_SHARED_MEMORY_HEAP_H_