Decouple GamepadSharedMemory into Blink.

content/renderer/gamepad_shared_memory_reader.cc

Index: content/renderer/gamepad_shared_memory_reader.cc
diff --git a/content/renderer/gamepad_shared_memory_reader.cc b/content/renderer/gamepad_shared_memory_reader.cc
deleted file mode 100644
index 62dd301c126f28333882cb1061018ae3efc1ec79..0000000000000000000000000000000000000000
--- a/content/renderer/gamepad_shared_memory_reader.cc
+++ /dev/null
@@ -1,135 +0,0 @@
-// 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/metrics/histogram_macros.h"
-#include "base/trace_event/trace_event.h"
-#include "content/public/renderer/render_thread.h"
-#include "content/renderer/renderer_blink_platform_impl.h"
-#include "ipc/ipc_sync_message_filter.h"
-#include "services/service_manager/public/cpp/interface_provider.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),
-      ever_interacted_with_(false),
-      binding_(this) {
-  if (thread) {
-    thread->GetRemoteInterfaces()->GetInterface(
-        mojo::GetProxy(&gamepad_monitor_));
-    gamepad_monitor_->SetObserver(binding_.CreateInterfacePtrAndBind());
-  }
-}
-
-void GamepadSharedMemoryReader::SendStartMessage() {
-  if (gamepad_monitor_) {
-    gamepad_monitor_->GamepadStartPolling(&renderer_shared_buffer_handle_);
-  }
-}
-
-void GamepadSharedMemoryReader::SendStopMessage() {
-  if (gamepad_monitor_) {
-    gamepad_monitor_->GamepadStopPolling();
-  }
-}
-
-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 = renderer_shared_buffer_handle_.is_valid();
-  UMA_HISTOGRAM_BOOLEAN("Gamepad.ValidSharedMemoryHandle", valid_handle);
-  if (!valid_handle)
-    return;
-
-  renderer_shared_buffer_mapping_ =
-      renderer_shared_buffer_handle_->Map(sizeof(GamepadHardwareBuffer));
-  CHECK(renderer_shared_buffer_mapping_);
-  void* memory = renderer_shared_buffer_mapping_.get();
-  CHECK(memory);
-  gamepad_hardware_buffer_ =
-      static_cast<GamepadHardwareBuffer*>(memory);
-}
-
-void GamepadSharedMemoryReader::SampleGamepads(blink::WebGamepads& gamepads) {
-  // Blink should have started observing at that point.
-  CHECK(is_observing());
-
-  // ==========
-  //   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");
-
-  if (!renderer_shared_buffer_handle_.is_valid())
-    return;
-
-  // Only try to read this many times before failing to avoid waiting here
-  // very long in case of contention with the writer. TODO(scottmg) Tune this
-  // number (as low as 1?) if histogram shows distribution as mostly
-  // 0-and-maximum.
-  const int kMaximumContentionCount = 10;
-  int contention_count = -1;
-  base::subtle::Atomic32 version;
-  do {
-    version = gamepad_hardware_buffer_->seqlock.ReadBegin();
-    memcpy(&read_into, &gamepad_hardware_buffer_->data, sizeof(read_into));
-    ++contention_count;
-    if (contention_count == kMaximumContentionCount)
-      break;
-  } while (gamepad_hardware_buffer_->seqlock.ReadRetry(version));
-  UMA_HISTOGRAM_COUNTS("Gamepad.ReadContentionCount", contention_count);
-
-  if (contention_count >= kMaximumContentionCount) {
-    // We failed to successfully read, presumably because the hardware
-    // thread was taking unusually long. Don't copy the data to the output
-    // buffer, and simply leave what was there before.
-    return;
-  }
-
-  // New data was read successfully, copy it into the output buffer.
-  memcpy(&gamepads, &read_into, sizeof(gamepads));
-
-  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;
-  }
-}
-
-GamepadSharedMemoryReader::~GamepadSharedMemoryReader() {
-  StopIfObserving();
-}
-
-void GamepadSharedMemoryReader::GamepadConnected(
-    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);
-}
-
-void GamepadSharedMemoryReader::GamepadDisconnected(
-    int index,
-    const blink::WebGamepad& gamepad) {
-  if (listener())
-    listener()->didDisconnectGamepad(index, gamepad);
-}
-
-} // namespace content