Device Service: Decouple Wake Lock from //content

device/wake_lock/wake_lock_service_context.h

Index: device/wake_lock/wake_lock_service_context.h
diff --git a/device/wake_lock/wake_lock_service_context.h b/device/wake_lock/wake_lock_service_context.h
index 01e7ebef29d1c6df794266af38e405b3ef41176d..0baa1a79c394dfe79c5f460ba35fdf2da2533dbf 100644
--- a/device/wake_lock/wake_lock_service_context.h
+++ b/device/wake_lock/wake_lock_service_context.h
@@ -12,25 +12,47 @@
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner.h"
+#include "device/wake_lock/public/interfaces/wake_lock_context.mojom.h"
 #include "device/wake_lock/wake_lock_service_impl.h"
+#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
+#include "mojo/public/cpp/bindings/strong_binding_set.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace device {
 
 class PowerSaveBlocker;
 
-class WakeLockServiceContext {
+// Callback that maps a context ID to the NativeView associated with
+// that context. This callback is provided to the Device Service by its
+// embedder.
+using WakeLockContextCallback = base::Callback<gfx::NativeView(int)>;
+
+// Serves requests for WakeLockService connections within a given context.
+
+// Note that the lifetime model of WakeLockContext is somewhat complex: It must
+// stay alive as long as either
+// (1) Its Mojo connection is still valid (as the client might make future
+// GetWakeLock() calls) OR
+// (2) There are still live WakeLock instances that it has instantiated (since
+// they call into it when they receive Mojo requests from *their* clients).
+// Consequently, WakeLockContext monitors the state of the connections described
+// in (1) and (2), dying only when *all* of those connections go away.
+class WakeLockServiceContext : public mojom::WakeLockContext {
  public:
   WakeLockServiceContext(
+      mojom::WakeLockContextRequest request,
+      int context_id,
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
-      base::Callback<gfx::NativeView()> native_view_getter);
-  ~WakeLockServiceContext();
+      const WakeLockContextCallback& native_view_getter);
+  ~WakeLockServiceContext() override;
 
-  // Creates a WakeLockServiceImpl that is strongly bound to |request|.
-  void CreateService(mojo::InterfaceRequest<mojom::WakeLockService> request);
+  // mojom::WakeLockContext:
+  void GetWakeLock(
+      mojo::InterfaceRequest<mojom::WakeLockService> request) override;
+  void HasWakeLockForTests(
+      const HasWakeLockForTestsCallback& callback) override;
 
   // Requests wake lock.
   void RequestWakeLock();
@@ -38,13 +60,14 @@ class WakeLockServiceContext {
   // Cancels pending wake lock request.
   void CancelWakeLock();
 
-  // Used by tests.
-  bool HasWakeLockForTests() const;
-
  private:
   void CreateWakeLock();
   void RemoveWakeLock();
   void UpdateWakeLock();
+  void OnContextBindingError();
+
+  // Checks whether this instance is still needed, and if not, destroys it.
+  void DestroyIfNoLongerNeeded();
 
   scoped_refptr<base::SequencedTaskRunner> main_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
@@ -53,9 +76,16 @@ class WakeLockServiceContext {
 
   // The actual power save blocker for screen.
   std::unique_ptr<PowerSaveBlocker> wake_lock_;
-  base::Callback<gfx::NativeView()> native_view_getter_;
 
-  base::WeakPtrFactory<WakeLockServiceContext> weak_factory_;
+#if defined(OS_ANDROID)
+  int context_id_;
+  WakeLockContextCallback native_view_getter_;
+#endif
+
+  mojo::Binding<mojom::WakeLockContext> context_binding_;
+  bool context_binding_encountered_error_;
+
+  mojo::StrongBindingSet<mojom::WakeLockService> wake_lock_bindings_;
 
   DISALLOW_COPY_AND_ASSIGN(WakeLockServiceContext);
 };