Limit the total memory usage for Stream instances

content/browser/streams/stream_registry.h

 // Copyright (c) 2013 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_BROWSER_STREAMS_STREAM_REGISTRY_H_
 #define CONTENT_BROWSER_STREAMS_STREAM_REGISTRY_H_
 
 #include <map>
 
 #include "base/basictypes.h"
@@ skipping 14 matching lines @@
 
   // Registers a stream, and sets its URL.
   void RegisterStream(scoped_refptr<Stream> stream);
 
   // Clones a stream.  Returns true on success, or false if |src_url| doesn't
   // exist.
   bool CloneStream(const GURL& url, const GURL& src_url);
 
   void UnregisterStream(const GURL& url);
 
+  // Called by Stream instances to request increase of memory usage. If the
+  // total memory usage for this registry is going to exceed the limit,
+  // returns false. Otherwise, updates |total_memory_usage_| and returns true.
+  //
+  // |current_size| is the up-to-date size of ByteStream of the Stream instance
+  // and |increase| must be the amount of data going to be added to the Stream
+  // instance.
+  bool UpdateMemoryUsage(const GURL& url, size_t current_size, size_t increase);
+
   // Gets the stream associated with |url|.  Returns NULL if there is no such
   // stream.
   scoped_refptr<Stream> GetStream(const GURL& url);
 
+  void set_max_memory_usage_for_testing(size_t size) {
+    max_memory_usage_ = size;
+  }
+
  private:
   typedef std::map<GURL, scoped_refptr<Stream> > StreamMap;
 
   StreamMap streams_;
 
+  size_t total_memory_usage_;
+
+  // Maximum amount of memory allowed to use for Stream instances registered
+  // with this registry.
+  size_t max_memory_usage_;
+
   DISALLOW_COPY_AND_ASSIGN(StreamRegistry);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_STREAMS_STREAM_REGISTRY_H_
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