Add blink::ServiceRegistry and expose it from LocalFrame and Platform.

third_party/WebKit/Source/platform/battery/battery_dispatcher_proxy.cc

Index: third_party/WebKit/Source/platform/battery/battery_dispatcher_proxy.cc
diff --git a/third_party/WebKit/Source/platform/battery/battery_dispatcher_proxy.cc b/third_party/WebKit/Source/platform/battery/battery_dispatcher_proxy.cc
index 1d052dddaf732d20cb99c6bec5acca217d3c4538..eaa953265f088c46969ecc390a62a10659fe4307 100644
--- a/third_party/WebKit/Source/platform/battery/battery_dispatcher_proxy.cc
+++ b/third_party/WebKit/Source/platform/battery/battery_dispatcher_proxy.cc
@@ -7,6 +7,7 @@
 #include "platform/battery/battery_status.h"
 #include "platform/threading/BindForMojo.h"
 #include "public/platform/Platform.h"
+#include "public/platform/ServiceRegistry.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
@@ -20,7 +21,11 @@ BatteryDispatcherProxy::~BatteryDispatcherProxy() {}
 
 void BatteryDispatcherProxy::StartListening() {
   ASSERT(!monitor_.is_bound());
-  Platform::current()->connectToRemoteService(mojo::GetProxy(&monitor_));
+  if (!Platform::current()->serviceRegistry())

[esprehn, 2016/03/29 05:26:20]

how do we get here with a null registry? I think that should be a fatal error.
The old code certainly assumed it wasn't possible.

[Sam McNally, 2016/03/30 00:20:53]

The equivalent of a null registry here would have been a no-op
Platform::connectToRemoteService() implementation.

+      return;
+
+  Platform::current()->serviceRegistry()->connectToRemoteService(
+      mojo::GetProxy(&monitor_));
   // monitor_ can be null during testing.
   if (monitor_)
     QueryNextStatus();