Convert device_sensors to use mojo.

content/renderer/device_sensors/device_sensor_event_pump.h

Index: content/renderer/device_sensors/device_sensor_event_pump.h
diff --git a/content/renderer/device_sensors/device_sensor_event_pump.h b/content/renderer/device_sensors/device_sensor_event_pump.h
index 46252a7cc120a74b72efa1da43a769c71d4b1929..8d10982004abd2494250b08278783e44e98a93ac 100644
--- a/content/renderer/device_sensors/device_sensor_event_pump.h
+++ b/content/renderer/device_sensors/device_sensor_event_pump.h
@@ -9,10 +9,53 @@
 #include "base/memory/shared_memory.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
+#include "content/public/common/service_registry.h"
 #include "content/public/renderer/platform_event_observer.h"
+#include "content/renderer/render_thread_impl.h"
+#include "mojo/public/cpp/system/platform_handle.h"
 
 namespace content {
 
+template <typename Base, typename MojoInterface>
+class CONTENT_EXPORT DeviceSensorMojoClientMixin : public Base {
+ public:
+  template <typename... Args>
+  explicit DeviceSensorMojoClientMixin(Args&&... args)
+      : Base(std::forward<Args>(args)...) {}
+
+  void SendStartMessage() override {
+    GetMojoInterface().StartPolling(
+        base::Bind(&DeviceSensorMojoClientMixin<Base, MojoInterface>::DidStart,

[dcheng, 2016/07/04 03:39:49]

Please include bind.h and bind_helpers.h.

[Sam McNally, 2016/07/04 08:31:39]

Done.

+                   base::Unretained(this)));
+  }
+  void SendStopMessage() override { GetMojoInterface().StopPolling(); }
+
+ protected:
+  MojoInterface& GetMojoInterface() {

[dcheng, 2016/07/04 03:39:49]

Why does this happen in a GetMojoInterface() helper rather than in the ctor?

[Sam McNally, 2016/07/04 08:31:39]

Done.

+    if (!mojo_interface_) {
+      mojo::InterfaceRequest<MojoInterface> request =
+          mojo::GetProxy(&mojo_interface_);
+
+      // When running layout tests, those observers should not listen to the
+      // actual hardware changes. In order to make that happen, don't connect
+      // the other end of the mojo pipe to anything.
+      if (!RenderThreadImpl::current() ||
+          !RenderThreadImpl::current()->layout_test_mode()) {

[dcheng, 2016/07/04 03:39:50]

Is this check still needed with Mojo? My understanding is that layout tests can
use JS mocks for Mojo stuff now: https://codereview.chromium.org/1836203002/

That would obsolete this, right?

(A followup for this is fine, I'm just trying to make sure I understand the
current state of affairs)

[Sam McNally, 2016/07/04 08:31:38]

Yes, the layout tests haven't been converted to that style. To convert those
layout tests, we'd need to expose mojo shared buffers to the JS API.

+        RenderThread::Get()->GetRemoteInterfaces()->GetInterface(
+            std::move(request));
+      }
+    }
+    return *mojo_interface_;
+  }
+
+  void DidStart(mojo::ScopedSharedBufferHandle buffer_handle) {
+    Base::DidStart(std::move(buffer_handle));
+  }
+
+ private:
+  mojo::InterfacePtr<MojoInterface> mojo_interface_;
+};
+
 template <typename ListenerType>
 class CONTENT_EXPORT DeviceSensorEventPump
     : NON_EXPORTED_BASE(public PlatformEventObserver<ListenerType>) {
@@ -71,7 +114,7 @@ class CONTENT_EXPORT DeviceSensorEventPump
       PENDING_START
   };
 
-  void OnDidStart(base::SharedMemoryHandle handle) {
+  void DidStart(mojo::ScopedSharedBufferHandle buffer_handle) {
     DVLOG(2) << "did start sensor event pump";
 
     if (state_ != PENDING_START)
@@ -79,6 +122,11 @@ class CONTENT_EXPORT DeviceSensorEventPump
 
     DCHECK(!timer_.IsRunning());
 
+    base::SharedMemoryHandle handle;
+    MojoResult result = mojo::UnwrapSharedMemoryHandle(
+        std::move(buffer_handle), &handle, nullptr, nullptr);
+    DCHECK_EQ(MOJO_RESULT_OK, result);
+
     if (InitializeReader(handle)) {
       timer_.Start(FROM_HERE,
                    base::TimeDelta::FromMicroseconds(pump_delay_microseconds_),