bluetooth: Move writeValue to mojo

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index 16d21e608290088b5a8f2d2f6161ed464fe4fe05..0d1465cff4ef1e4aa75d2adc62ba6e594fac5ebc 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -63,6 +63,12 @@ class FilePath;
 class ListValue;
 }
 
+namespace blink {
+namespace mojom {
+class WebBluetoothService;
+}
+}
+
 namespace content {
 
 class CrossProcessFrameConnector;
@@ -83,6 +89,7 @@ class RenderWidgetHostViewBase;
 class ResourceRequestBody;
 class StreamHandle;
 class TimeoutMonitor;
+class WebBluetoothServiceImpl;
 struct ContextMenuParams;
 struct GlobalRequestID;
 struct Referrer;
@@ -736,6 +743,10 @@ class CONTENT_EXPORT RenderFrameHostImpl : public RenderFrameHost,
   FrameTreeNode* FindAndVerifyChild(int32_t child_frame_routing_id,
                                     bad_message::BadMessageReason reason);
 
+  // Creates a Web Bluetooth Service owned by the frame.
+  void CreateWebBluetoothService(
+      mojo::InterfaceRequest<blink::mojom::WebBluetoothService> request);
+
   // Allows tests to disable the swapout event timer to simulate bugs that
   // happen before it fires (to avoid flakiness).
   void ResetSwapOutTimerForTesting();
@@ -879,6 +890,8 @@ class CONTENT_EXPORT RenderFrameHostImpl : public RenderFrameHost,
   scoped_ptr<ServiceRegistryAndroid> service_registry_android_;
 #endif
 
+  scoped_ptr<WebBluetoothServiceImpl> web_bluetooth_service_;

[scheib, 2016/03/31 04:17:51]

WebBluetoothServiceImpl implies that it would prefer to have a StrongBinding
that had the Impl destruct when the pipe closes. It could, it seems, if
RenderFrameHostImpl a weak pointer here and destroyed the
WebBluetoothServiceImpl in ~RenderFrameHostImpl.

But, current code pattern seems fine, which makes me think the comment is too
strong in WebBluetoothServiceImpl "so we can't use the self-deleting behavior of
a StrongBinding" -- it implies that there's a deficiency to not using
StrongBinding.

[Jeffrey Yasskin, 2016/03/31 15:26:16]

That wording comes from  me, I think. My idea was that it's always nicer not to
have a half-working object: if the pipe is closed but the object still exists,
that's one extra state to deal with. If we can use a StrongBinding, then that
state doesn't exist by construction. But here, we need to call into the object
via the RenderFrameHost, so we either have the half-working state in
WebBluetoothServiceImpl or in RenderFrameHost, and maybe it's simpler to
encapsulate it in WebBluetoothServiceImpl. I don't have a strong opinion about
which to use, but the comments should explain why we used the one we did.

[ortuno, 2016/03/31 16:56:44]

When I was designing this I had to decide between using a "Binding" and having
the frame own the Service or using a StrongBinding and juggle the lifetime of
the service between the pipe closing and the frame being removed (I would have
had to do this by implementing a couple of functions of WebContentsObserver; I
hadn't considered using a WeakPtr in RenderFrameHostImpl)

I thought that making Frame own the service would make it much easier to reason
about the lifetime of the service and would result in less code.

I changed the comment for binding_.

+
   // The object managing the accessibility tree for this frame.
   scoped_ptr<BrowserAccessibilityManager> browser_accessibility_manager_;