gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/client/mapped_memory.h

Index: gpu/command_buffer/client/mapped_memory.h
diff --git a/gpu/command_buffer/client/mapped_memory.h b/gpu/command_buffer/client/mapped_memory.h
index b8f3129eb4a3cddf452e9fabe30ec62a1af12eda..7b0d87b5f4a711278a43bfe631b6d874f95be3d7 100644
--- a/gpu/command_buffer/client/mapped_memory.h
+++ b/gpu/command_buffer/client/mapped_memory.h
@@ -5,6 +5,7 @@
 #ifndef GPU_COMMAND_BUFFER_CLIENT_MAPPED_MEMORY_H_
 #define GPU_COMMAND_BUFFER_CLIENT_MAPPED_MEMORY_H_
 
+#include "base/bind.h"
 #include "base/memory/scoped_vector.h"
 #include "gpu/command_buffer/client/fenced_allocator.h"
 #include "gpu/command_buffer/common/buffer.h"
@@ -18,7 +19,10 @@ class CommandBufferHelper;
 // Manages a shared memory segment.
 class GPU_EXPORT MemoryChunk {
  public:
-  MemoryChunk(int32 shm_id, gpu::Buffer shm, CommandBufferHelper* helper);
+  MemoryChunk(int32 shm_id,
+              gpu::Buffer shm,
+              CommandBufferHelper* helper,
+              const base::Closure& poll_callback);
 
   // Gets the size of the largest free block that is available without waiting.
   unsigned int GetLargestFreeSizeWithoutWaiting() {
@@ -117,6 +121,7 @@ class GPU_EXPORT MappedMemoryManager {
   // |unused_memory_reclaim_limit|: When exceeded this causes pending memory
   // to be reclaimed before allocating more memory.
   MappedMemoryManager(CommandBufferHelper* helper,
+                      const base::Closure& poll_callback,
                       size_t unused_memory_reclaim_limit);
 
   ~MappedMemoryManager();
@@ -161,6 +166,15 @@ class GPU_EXPORT MappedMemoryManager {
     return chunks_.size();
   }
 
+  size_t bytes_in_use() const {
+    size_t bytes_in_use = 0;
+    for (size_t ii = 0; ii < chunks_.size(); ++ii) {
+      MemoryChunk* chunk = chunks_[ii];
+      bytes_in_use += chunk->bytes_in_use();
+    }
+    return bytes_in_use;
+  }
+
   // Used for testing
   size_t allocated_memory() const {
     return allocated_memory_;
@@ -172,6 +186,7 @@ class GPU_EXPORT MappedMemoryManager {
   // size a chunk is rounded up to.
   unsigned int chunk_size_multiple_;
   CommandBufferHelper* helper_;
+  base::Closure poll_callback_;
   MemoryChunkVector chunks_;
   size_t allocated_memory_;
   size_t max_free_bytes_;