Add cc::SharedBitmap::shared_memory_handle()

cc/resources/shared_bitmap.h

Index: cc/resources/shared_bitmap.h
diff --git a/cc/resources/shared_bitmap.h b/cc/resources/shared_bitmap.h
index 464ac5c6d4c020ed3cab876bc69c50a303843171..0604e966c9b19901fac2ccf1e9d66e86751e4211 100644
--- a/cc/resources/shared_bitmap.h
+++ b/cc/resources/shared_bitmap.h
@@ -14,6 +14,12 @@
 #include "gpu/command_buffer/common/mailbox.h"
 #include "ui/gfx/geometry/size.h"
 
+namespace base {
+

[danakj, 2017/05/31 16:10:31]

nit: remove whitespace

[hajimehoshi, 2017/06/01 04:47:58]

Done.

+class SharedMemoryHandle;
+

[danakj, 2017/05/31 16:10:31]

nit: remove whitespace

[hajimehoshi, 2017/06/01 04:47:58]

Done.

+}  // namespace base

[danakj, 2017/05/31 16:10:31]

nit: no need for this comment on such a short block

[hajimehoshi, 2017/06/01 04:47:57]

Done.

+
 namespace cc {
 typedef gpu::Mailbox SharedBitmapId;
 
@@ -30,6 +36,10 @@ class CC_EXPORT SharedBitmap {
 
   const SharedBitmapId& id() { return id_; }
 
+  // Returns the shared memory's handle when the back end is base::SharedMemory.
+  // Otherwise, this returns an invalid handle.
+  virtual base::SharedMemoryHandle shared_memory_handle() const;

[danakj, 2017/05/31 16:10:31]

Who will call this? You only implement this for the host subclass, so will the
caller not know that the type is HostSharedBitmap?

[hajimehoshi, 2017/06/01 04:47:58]

cc::ResourceProvider::Resource will call this. In
cc::ResourceProvider::OnMemoryDump, when a resource type is
RESOURCE_TYPE_BITMAP, resource's shared bitmap can be obtained but there is no
way to know if this is HostSharedBitmap or not.

[danakj, 2017/06/01 13:25:49]

Then why is there no override for ChildSharedBitmap as well? Do you only want to
count memory in the browser process?

[danakj, 2017/06/01 16:29:32]

Can you make this pure virtual? That would force us to not miss the subclass.

+
   // Returns true if the size is valid and false otherwise.
   static bool SizeInBytes(const gfx::Size& size, size_t* size_in_bytes);
   // Dies with a CRASH() if the size can not be represented as a positive number