Add shared bitmap managers for browser and renderer processes.

content/child/child_shared_bitmap_manager.cc

+// 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.
+
+#include "content/child/child_shared_bitmap_manager.h"
+
+#include "content/child/child_thread.h"
+#include "content/common/child_process_messages.h"
+#include "ui/gfx/size.h"
+
+namespace content {
+
+ChildSharedBitmapManager::ChildSharedBitmapManager(
+    scoped_refptr<ThreadSafeSender> sender)
+    : sender_(sender) {}
+
+ChildSharedBitmapManager::~ChildSharedBitmapManager() {}
+
+scoped_ptr<cc::SharedBitmap> ChildSharedBitmapManager::AllocateSharedBitmap(
+    gfx::Size size) {
+  TRACE_EVENT2("renderer",
+               "ChildSharedBitmapManager::AllocateSharedMemory",
+               "width",
+               size.width(),
+               "height",
+               size.height());
+  size_t memory_size = cc::SharedBitmap::GetSizeInBytes(size);
+  cc::SharedBitmapId id = cc::SharedBitmap::GenerateId();

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

It seems potentially problematic to me that the child is generating these ids,
can't it just ask for a size, and be returned an id?

+  scoped_ptr<base::SharedMemory> memory;
+#if defined(OS_POSIX)
+  base::SharedMemoryHandle handle;
+  sender_->Send(new ChildProcessHostMsg_SyncAllocateSharedBitmap(
+      memory_size, id, &handle));
+  memory = make_scoped_ptr(new base::SharedMemory(handle, false));
+  memory->Map(memory_size);
+#else
+  memory =
+      make_scoped_ptr(ChildThread::AllocateSharedMemory(memory_size, sender_));
+  CHECK(memory);
+  memory->Map(memory_size);
+  base::SharedMemoryHandle handle_to_send = memory->handle();
+  sender_->Send(
+      new ChildProcessHostMsg_AllocatedSharedBitmap(handle_to_send, id));
+#endif
+  return scoped_ptr<cc::SharedBitmap>(new cc::SharedBitmap(
+      memory.release(),
+      id,
+      base::Bind(&ChildSharedBitmapManager::FreeSharedMemory,
+                 base::Unretained(this))));
+}
+
+scoped_ptr<cc::SharedBitmap> ChildSharedBitmapManager::GetSharedBitmapFromId(
+    gfx::Size,
+    const cc::SharedBitmapId&) {
+  return scoped_ptr<cc::SharedBitmap>();

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

Future: It looks like ResourceProvider::ReceiveFromChild currently calls this
unconditionally, when it's just going to give a NULL back. Maybe we could
instead delay that call to where the RP actually tries to use the pixels field
instead, and have this function NOTREACHED()?

[danakj, 2014/01/31 17:44:22]

dongseong pointed out that returning NULL here causes the ResourceProvider to
actually drop the resource in ReceiveFromChild. So if renderer is using this
(looks like it does), then it will be unable to receive and pass on software
resources without addressing this.

+}
+
+scoped_ptr<cc::SharedBitmap> ChildSharedBitmapManager::GetBitmapForSharedMemory(
+    base::SharedMemory* mem) {
+  cc::SharedBitmapId id = cc::SharedBitmap::GenerateId();
+  base::SharedMemoryHandle handle_to_send = mem->handle();

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

Could the id here come from the browser where the handle came from? 

+#if defined(OS_POSIX)
+  if (!mem->ShareToProcess(base::GetCurrentProcessHandle(), &handle_to_send))
+    return scoped_ptr<cc::SharedBitmap>();
+#endif
+  sender_->Send(
+      new ChildProcessHostMsg_AllocatedSharedBitmap(handle_to_send, id));
+  return scoped_ptr<cc::SharedBitmap>(new cc::SharedBitmap(
+      mem,
+      id,
+      base::Bind(&ChildSharedBitmapManager::ReleaseSharedBitmap,
+                 base::Unretained(this))));
+}
+
+void ChildSharedBitmapManager::FreeSharedMemory(cc::SharedBitmap* bitmap) {
+  TRACE_EVENT0("renderer", "ChildSharedBitmapManager::FreeSharedMemory");
+  sender_->Send(new ChildProcessHostMsg_DeletedSharedBitmap(bitmap->id()));
+  delete bitmap->memory();
+}
+
+void ChildSharedBitmapManager::ReleaseSharedBitmap(cc::SharedBitmap* handle) {
+  sender_->Send(new ChildProcessHostMsg_DeletedSharedBitmap(handle->id()));

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

TRACE_EVENT here?

+}
+
+}  // namespace content