Revert "Refactor code listening to platform events in content/renderer/."

content/renderer/gamepad_shared_memory_reader.cc

 // Copyright (c) 2012 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 "content/renderer/gamepad_shared_memory_reader.h"
 
 #include "base/debug/trace_event.h"
 #include "base/metrics/histogram.h"
 #include "content/common/gamepad_hardware_buffer.h"
 #include "content/common/gamepad_user_gesture.h"
 #include "content/public/renderer/render_thread.h"
 #include "content/renderer/renderer_webkitplatformsupport_impl.h"
 #include "ipc/ipc_sync_message_filter.h"
 #include "third_party/WebKit/public/platform/WebGamepadListener.h"
-#include "third_party/WebKit/public/platform/WebPlatformEventListener.h"
 
 namespace content {
 
-GamepadSharedMemoryReader::GamepadSharedMemoryReader(RenderThread* thread)
-    : RendererGamepadProvider(thread),
-      gamepad_hardware_buffer_(NULL),
+GamepadSharedMemoryReader::GamepadSharedMemoryReader(
+    RendererWebKitPlatformSupportImpl* webkit_platform_support)
+    : gamepad_hardware_buffer_(NULL),
+      gamepad_listener_(NULL),
+      is_polling_(false),
       ever_interacted_with_(false) {
+  webkit_platform_support->set_gamepad_provider(this);
 }
 
-void GamepadSharedMemoryReader::SendStartMessage() {
+void GamepadSharedMemoryReader::StartPollingIfNecessary() {
+  if (is_polling_)
+    return;
+
   CHECK(RenderThread::Get()->Send(new GamepadHostMsg_StartPolling(
       &renderer_shared_memory_handle_)));
-}
-
-void GamepadSharedMemoryReader::SendStopMessage() {
-    RenderThread::Get()->Send(new GamepadHostMsg_StopPolling());
-}
-
-void GamepadSharedMemoryReader::Start(
-    blink::WebPlatformEventListener* listener) {
-  PlatformEventObserver::Start(listener);
 
   // If we don't get a valid handle from the browser, don't try to Map (we're
   // probably out of memory or file handles).
   bool valid_handle = base::SharedMemory::IsHandleValid(
       renderer_shared_memory_handle_);
   UMA_HISTOGRAM_BOOLEAN("Gamepad.ValidSharedMemoryHandle", valid_handle);
   if (!valid_handle)
     return;
 
   renderer_shared_memory_.reset(
       new base::SharedMemory(renderer_shared_memory_handle_, true));
   CHECK(renderer_shared_memory_->Map(sizeof(GamepadHardwareBuffer)));
   void *memory = renderer_shared_memory_->memory();
   CHECK(memory);
   gamepad_hardware_buffer_ =
       static_cast<GamepadHardwareBuffer*>(memory);
+
+  is_polling_ = true;
+}
+
+void GamepadSharedMemoryReader::StopPollingIfNecessary() {
+  if (is_polling_) {
+    RenderThread::Get()->Send(new GamepadHostMsg_StopPolling());
+    is_polling_ = false;
+  }
 }
 
 void GamepadSharedMemoryReader::SampleGamepads(blink::WebGamepads& gamepads) {
-  // Blink should have started observing at that point.
-  CHECK(is_observing());
+  // Blink should set the listener before start sampling.
+  CHECK(gamepad_listener_);
+
+  StartPollingIfNecessary();
+  if (!is_polling_)
+    return;
 
   // ==========
   //   DANGER
   // ==========
   //
   // This logic is duplicated in Pepper as well. If you change it, that also
   // needs to be in sync. See ppapi/proxy/gamepad_resource.cc.
   blink::WebGamepads read_into;
   TRACE_EVENT0("GAMEPAD", "SampleGamepads");
 
@@ skipping 29 matching lines @@
   if (!ever_interacted_with_) {
     // Clear the connected flag if the user hasn't interacted with any of the
     // gamepads to prevent fingerprinting. The actual data is not cleared.
     // WebKit will only copy out data into the JS buffers for connected
     // gamepads so this is sufficient.
     for (unsigned i = 0; i < blink::WebGamepads::itemsLengthCap; i++)
       gamepads.items[i].connected = false;
   }
 }
 
+void GamepadSharedMemoryReader::SetGamepadListener(
+    blink::WebGamepadListener* listener) {
+  gamepad_listener_ = listener;
+  if (gamepad_listener_) {
+    // Polling has to be started rigth now and not just on the first sampling
+    // because want to get connection events from now.
+    StartPollingIfNecessary();
+  } else {
+    StopPollingIfNecessary();
+  }
+}
+
 GamepadSharedMemoryReader::~GamepadSharedMemoryReader() {
+  StopPollingIfNecessary();
 }
 
 bool GamepadSharedMemoryReader::OnControlMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(GamepadSharedMemoryReader, message)
     IPC_MESSAGE_HANDLER(GamepadMsg_GamepadConnected, OnGamepadConnected)
     IPC_MESSAGE_HANDLER(GamepadMsg_GamepadDisconnected, OnGamepadDisconnected)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 void GamepadSharedMemoryReader::OnGamepadConnected(
     int index,
     const blink::WebGamepad& gamepad) {
   // The browser already checks if the user actually interacted with a device.
   ever_interacted_with_ = true;
 
-  if (listener())
-    listener()->didConnectGamepad(index, gamepad);
+  if (gamepad_listener_)
+    gamepad_listener_->didConnectGamepad(index, gamepad);
 }
 
 void GamepadSharedMemoryReader::OnGamepadDisconnected(
     int index,
     const blink::WebGamepad& gamepad) {
-  if (listener())
-    listener()->didDisconnectGamepad(index, gamepad);
+  if (gamepad_listener_)
+    gamepad_listener_->didDisconnectGamepad(index, gamepad);
 }
 
 } // namespace content