Add shared bitmap managers for browser and renderer processes.

content/common/host_shared_bitmap_manager.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.

[danakj, 2014/01/30 22:59:01]

You have this file in content/common/. Would a renderer that had an OOP iframe
in it end up owning a HostSharedBitmapManager, or is it just the browser process
that owns one of these? I was expecting the latter so this file's place was
surprising.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/common/host_shared_bitmap_manager.h"
+
+#include "base/lazy_instance.h"
+#include "base/memory/ref_counted.h"
+#include "content/common/view_messages.h"
+#include "ui/gfx/size.h"
+
+namespace content {
+
+class BitmapData : public base::RefCountedThreadSafe<BitmapData> {
+ public:
+  BitmapData(base::ProcessHandle process_handle,
+             base::SharedMemoryHandle memory_handle)
+      : process_handle(process_handle), memory_handle(memory_handle) {}
+  base::ProcessHandle process_handle;
+  base::SharedMemoryHandle memory_handle;
+  scoped_ptr<base::SharedMemory> memory;
+
+ private:
+  friend class base::RefCountedThreadSafe<BitmapData>;
+  ~BitmapData() {}
+  DISALLOW_COPY_AND_ASSIGN(BitmapData);
+};
+
+// Holds a reference on the memory to keep it alive.
+void FreeSharedMemory(scoped_refptr<BitmapData> data,
+                      cc::SharedBitmap* bitmap) {}
+
+base::LazyInstance<HostSharedBitmapManager> g_shared_memory_manager =

[danakj, 2014/01/30 22:59:01]

Naive question maybe, as this seems to be the way things are often done in the
browser process.. but.. Is there someone that could own this instead of making
it a global?

+    LAZY_INSTANCE_INITIALIZER;
+
+HostSharedBitmapManager::HostSharedBitmapManager() {}
+HostSharedBitmapManager::~HostSharedBitmapManager() {}
+
+HostSharedBitmapManager* HostSharedBitmapManager::current() {
+  return g_shared_memory_manager.Pointer();
+}
+
+scoped_ptr<cc::SharedBitmap> HostSharedBitmapManager::AllocateSharedBitmap(
+    gfx::Size size) {
+  return scoped_ptr<cc::SharedBitmap>();

[danakj, 2014/01/30 22:59:01]

NOTREACHED() and a comment?

+}
+
+scoped_ptr<cc::SharedBitmap> HostSharedBitmapManager::GetSharedBitmapFromId(
+    gfx::Size size,
+    const cc::SharedBitmapId& id) {
+  base::AutoLock lock(lock_);
+  BitmapMap::iterator it = handle_map_.find(id);
+  if (it == handle_map_.end())
+    return scoped_ptr<cc::SharedBitmap>();
+
+  BitmapData* data = it->second.get();
+
+  size_t mapped_size = cc::SharedBitmap::GetSizeInBytes(size);
+  if (!data->memory->memory()) {
+    TRACE_EVENT0("renderer_host",
+                 "HostSharedBitmapManager::GetSharedBitmapFromId");
+    if (!data->memory->Map(mapped_size)) {
+      return scoped_ptr<cc::SharedBitmap>();
+    }
+  } else if (data->memory->mapped_size() < mapped_size) {
+    return scoped_ptr<cc::SharedBitmap>();
+  }
+
+  scoped_ptr<cc::SharedBitmap> bitmap(new cc::SharedBitmap(
+      data->memory.get(), id, base::Bind(&FreeSharedMemory, it->second)));
+
+  return bitmap.Pass();
+}
+
+scoped_ptr<cc::SharedBitmap> HostSharedBitmapManager::GetBitmapForSharedMemory(
+    base::SharedMemory*) {
+  return scoped_ptr<cc::SharedBitmap>();
+}
+
+void HostSharedBitmapManager::ChildAllocatedSharedBitmap(
+    const base::SharedMemoryHandle& handle,
+    base::ProcessHandle process_handle,
+    const cc::SharedBitmapId& id) {
+  base::AutoLock lock(lock_);
+  if (handle_map_.find(id) != handle_map_.end())
+    return;
+  scoped_refptr<BitmapData> data(new BitmapData(process_handle, handle));
+
+  handle_map_[id] = data;
+  process_map_[process_handle].insert(id);
+#if defined(OS_WIN)
+  data->memory = make_scoped_ptr(
+      new base::SharedMemory(data->memory_handle, false, data->process_handle));
+#else
+  data->memory =
+      make_scoped_ptr(new base::SharedMemory(data->memory_handle, false));
+#endif
+}
+
+void HostSharedBitmapManager::AllocateSharedBitmapForChild(
+    base::ProcessHandle process_handle,
+    size_t buffer_size,
+    const cc::SharedBitmapId& id,
+    base::SharedMemoryHandle* shared_memory_handle) {
+  base::AutoLock lock(lock_);
+  if (handle_map_.find(id) != handle_map_.end()) {
+    *shared_memory_handle = base::SharedMemory::NULLHandle();
+    return;
+  }
+  scoped_ptr<base::SharedMemory> shared_memory(new base::SharedMemory);
+  if (!shared_memory->CreateAndMapAnonymous(buffer_size)) {
+    NOTREACHED() << "Cannot create shared memory buffer";

[danakj, 2014/01/30 22:59:01]

Not a fan of NOTREACHED/DCHECK on a path that also tries to handle the case.
Then we can't write a test for this code path. Either LOG(FATAL) and stop trying
to handle the case, or LOG(ERROR) and handle it as you are, IMO.

+    *shared_memory_handle = base::SharedMemory::NULLHandle();
+    return;
+  }
+
+  scoped_refptr<BitmapData> data(
+      new BitmapData(process_handle, shared_memory->handle()));
+  data->memory = shared_memory.Pass();
+
+  handle_map_[id] = data;
+  process_map_[process_handle].insert(id);
+  if (!data->memory->ShareToProcess(process_handle, shared_memory_handle)) {
+    NOTREACHED() << "Cannot share shared memory buffer";

[danakj, 2014/01/30 22:59:01]

Same here.

+    *shared_memory_handle = base::SharedMemory::NULLHandle();
+    return;
+  }
+}
+
+void HostSharedBitmapManager::ChildDeletedSharedBitmap(
+    const cc::SharedBitmapId& id) {
+  base::AutoLock lock(lock_);
+  BitmapMap::iterator it = handle_map_.find(id);
+  if (it == handle_map_.end())
+    return;
+  std::set<cc::SharedBitmapId>& res = process_map_[it->second->process_handle];
+  res.erase(id);
+  handle_map_.erase(it);
+}
+
+void HostSharedBitmapManager::ProcessRemoved(
+    base::ProcessHandle process_handle) {
+  base::AutoLock lock(lock_);
+  ProcessMap::iterator proc_it = process_map_.find(process_handle);
+  if (proc_it == process_map_.end())
+    return;
+  std::set<cc::SharedBitmapId>& res = proc_it->second;
+
+  for (std::set<cc::SharedBitmapId>::iterator it = res.begin(); it != res.end();
+       ++it) {
+    handle_map_.erase(*it);
+  }
+  process_map_.erase(proc_it);
+}
+
+}  // namespace content