[sensors] Fix flakiness in generic sensors tests

third_party/WebKit/Source/modules/sensor/SensorProviderProxy.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/sensor/SensorProviderProxy.h"
 
 #include "modules/sensor/SensorProxy.h"
 #include "modules/sensor/SensorReading.h"
 #include "platform/mojo/MojoHelper.h"
 #include "public/platform/InterfaceProvider.h"
 #include "public/platform/Platform.h"
 
 namespace blink {
 
 // SensorProviderProxy
 SensorProviderProxy::SensorProviderProxy(LocalFrame* frame) {
+  initializeSensorProviderIfNeeded(frame);
+}
+
+void SensorProviderProxy::initializeSensorProviderIfNeeded(LocalFrame* frame) {
+  if (m_sensorProvider)
+    return;
+
   frame->interfaceProvider()->getInterface(mojo::GetProxy(&m_sensorProvider));
   m_sensorProvider.set_connection_error_handler(convertToBaseCallback(
       WTF::bind(&SensorProviderProxy::onSensorProviderConnectionError,
                 wrapWeakPersistent(this))));
 }
 
 const char* SensorProviderProxy::supplementName() {
   return "SensorProvider";
 }
 
 SensorProviderProxy* SensorProviderProxy::from(LocalFrame* frame) {
   DCHECK(frame);
   SensorProviderProxy* result = static_cast<SensorProviderProxy*>(
       Supplement<LocalFrame>::from(*frame, supplementName()));
   if (!result) {
     result = new SensorProviderProxy(frame);
     Supplement<LocalFrame>::provideTo(*frame, supplementName(), result);
+  } else {
+    result->initializeSensorProviderIfNeeded(frame);

[Mikhail, 2016/11/28 10:42:51]

maybe split methods, like "isInitialized() const" + "initialize()", like we have
for SensorProxy. Then,

if (!provider->isInitialized())
   provider->initialize()

and call 'initialize()' from ctor.

[shalamov, 2016/11/28 12:50:54]

Done.

   }
   return result;
 }
 
 SensorProviderProxy::~SensorProviderProxy() {}
 
 DEFINE_TRACE(SensorProviderProxy) {
   visitor->trace(m_sensorProxies);
   Supplement<LocalFrame>::trace(visitor);
 }
@@ skipping 15 matching lines @@
     device::mojom::blink::SensorType type) {
   for (SensorProxy* sensor : m_sensorProxies) {
     // TODO(Mikhail) : Hash sensors by type for efficiency.
     if (sensor->type() == type)
       return sensor;
   }
 
   return nullptr;
 }
 
+device::mojom::blink::SensorProvider* SensorProviderProxy::getSensorProvider()

[Mikhail, 2016/11/28 10:42:51]

why move it here (and rename)? IMO it's fine to keep it inline.

[shalamov, 2016/11/28 12:50:54]

Wanted to make lazy getter, but then noticed that frame is required. Forgot to
move it back.

Done.

+    const {
+  return m_sensorProvider.get();
+}
+
 void SensorProviderProxy::onSensorProviderConnectionError() {
   if (!Platform::current()) {
     // TODO(rockot): Clean this up once renderer shutdown sequence is fixed.
     return;
   }
 
   m_sensorProvider.reset();
   for (SensorProxy* sensor : m_sensorProxies)
     sensor->handleSensorError();
 }
 
 }  // namespace blink