Refactored gamepad polling to support dynamic sources

device/gamepad/gamepad_provider.h

Index: device/gamepad/gamepad_provider.h
diff --git a/device/gamepad/gamepad_provider.h b/device/gamepad/gamepad_provider.h
index 5d2e2b2eb9b744f646705cb2945d58ba4a98433b..3adf81439e5c039cd2ae0cd1176503d17a46f1bc 100644
--- a/device/gamepad/gamepad_provider.h
+++ b/device/gamepad/gamepad_provider.h
@@ -5,6 +5,8 @@
 #ifndef DEVICE_GAMEPAD_GAMEPAD_PROVIDER_H_
 #define DEVICE_GAMEPAD_GAMEPAD_PROVIDER_H_
 
+#include <stdint.h>
+
 #include <memory>
 #include <utility>
 #include <vector>
@@ -13,11 +15,11 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/shared_memory.h"
-#include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
 #include "base/system_monitor/system_monitor.h"
 #include "device/gamepad/gamepad_export.h"
 #include "device/gamepad/gamepad_shared_buffer.h"
+#include "device/gamepad/gamepad_standard_mappings.h"
 #include "third_party/WebKit/public/platform/WebGamepads.h"
 
 namespace base {
@@ -29,6 +31,57 @@ namespace device {
 
 class GamepadDataFetcher;
 
+enum GamepadSource {
+  GAMEPAD_SOURCE_NONE = 0,
+  GAMEPAD_SOURCE_ANDROID,
+  GAMEPAD_SOURCE_LINUX_UDEV,
+  GAMEPAD_SOURCE_MAC_HID,
+  GAMEPAD_SOURCE_MAC_XBOX,
+  GAMEPAD_SOURCE_TEST,
+  GAMEPAD_SOURCE_WIN_XINPUT,
+  GAMEPAD_SOURCE_WIN_RAW,
+};
+
+enum GamepadActiveState {
+  GAMEPAD_INACTIVE = 0,
+  GAMEPAD_ACTIVE,
+  GAMEPAD_NEWLY_ACTIVE,
+};
+
+struct PadState {
+  // Which data fetcher provided this gamepad's data.
+  GamepadSource source;
+  // Data fetcher-specific identifier for this gamepad.
+  int source_id;
+
+  // Indicates whether or not the gamepad is actively being updated
+  GamepadActiveState active_state;
+
+  // Gamepad data, unmapped.
+  blink::WebGamepad data;
+
+  // Functions to map from device data to standard layout, if available. May
+  // be null if no mapping is available or needed.
+  GamepadStandardMappingFunction mapper;
+
+  // Sanitization masks
+  // axis_mask and button_mask are bitfields that represent the reset state of
+  // each input. If a button or axis has ever reported 0 in the past the
+  // corresponding bit will be set to 1.
+
+  // If we ever increase the max axis count this will need to be updated.
+  static_assert(blink::WebGamepad::axesLengthCap <=
+                    std::numeric_limits<uint32_t>::digits,
+                "axis_mask is not large enough");
+  uint32_t axis_mask;
+
+  // If we ever increase the max button count this will need to be updated.
+  static_assert(blink::WebGamepad::buttonsLengthCap <=
+                    std::numeric_limits<uint32_t>::digits,
+                "button_mask is not large enough");
+  uint32_t button_mask;
+};
+
 class DEVICE_GAMEPAD_EXPORT GamepadConnectionChangeClient {
  public:
   virtual void OnGamepadConnectionChange(bool connected,
@@ -56,6 +109,9 @@ class DEVICE_GAMEPAD_EXPORT GamepadProvider
   base::SharedMemoryHandle GetSharedMemoryHandleForProcess(
       base::ProcessHandle renderer_process);
 
+  void AddGamepadDataFetcher(GamepadDataFetcher* fetcher);
+  void RemoveGamepadDataFetcher(GamepadDataFetcher* fetcher);
+
   void GetCurrentGamepadData(blink::WebGamepads* data);
 
   // Pause and resume the background polling thread. Can be called from any
@@ -70,12 +126,26 @@ class DEVICE_GAMEPAD_EXPORT GamepadProvider
   // base::SystemMonitor::DevicesChangedObserver implementation.
   void OnDevicesChanged(base::SystemMonitor::DeviceType type) override;
 
+  // Add a gamepad data fetcher. Takes ownership of |fetcher|.
+  void AddGamepadDataFetcher(std::unique_ptr<GamepadDataFetcher> fetcher);
+
+  // Remove gamepad data fetchers with the given source.
+  void RemoveSourceGamepadDataFetcher(GamepadSource source);
+
+  // Gets a PadState object for the given source and id. If the device hasn't
+  // been encountered before one of the remaining slots will be reserved for it.
+  // If no slots are available will return NULL.
+  PadState* GetPadState(GamepadSource source, int source_id);
+
+  void SetSanitizationEnabled(bool sanitize) { sanitize_ = sanitize; }
+
  private:
   void Initialize(std::unique_ptr<GamepadDataFetcher> fetcher);
 
   // Method for setting up the platform-specific data fetcher. Takes ownership
   // of |fetcher|.
-  void DoInitializePollingThread(std::unique_ptr<GamepadDataFetcher> fetcher);
+  void DoAddGamepadDataFetcher(std::unique_ptr<GamepadDataFetcher> fetcher);
+  void DoRemoveSourceGamepadDataFetcher(GamepadSource source);
 
   // Method for sending pause hints to the low-level data fetcher. Runs on
   // polling_thread_.
@@ -91,6 +161,9 @@ class DEVICE_GAMEPAD_EXPORT GamepadProvider
 
   // Checks the gamepad state to see if the user has interacted with it.
   void CheckForUserGesture();
+  void ClearPadState(PadState& state);
+
+  void MapAndSanitizeGamepadData(PadState* pad_state, blink::WebGamepad* pad);
 
   enum { kDesiredSamplingIntervalMs = 16 };
 
@@ -131,31 +204,14 @@ class DEVICE_GAMEPAD_EXPORT GamepadProvider
   bool devices_changed_;
 
   bool ever_had_user_gesture_;
+  bool sanitize_;
 
-  class PadState {
-   public:
-    PadState() { SetDisconnected(); }
-
-    bool Match(const blink::WebGamepad& pad) const;
-    void SetPad(const blink::WebGamepad& pad);
-    void SetDisconnected();
-    void AsWebGamepad(blink::WebGamepad* pad);
-
-    bool connected() const { return connected_; }
-
-   private:
-    bool connected_;
-    unsigned axes_length_;
-    unsigned buttons_length_;
-    blink::WebUChar id_[blink::WebGamepad::idLengthCap];
-    blink::WebUChar mapping_[blink::WebGamepad::mappingLengthCap];
-  };
-
-  // Used to detect connections and disconnections.
+  // Tracks the state of each gamepad slot.
   std::unique_ptr<PadState[]> pad_states_;
 
   // Only used on the polling thread.
-  std::unique_ptr<GamepadDataFetcher> data_fetcher_;
+  typedef std::vector<std::unique_ptr<GamepadDataFetcher>> GamepadFetcherVector;
+  GamepadFetcherVector data_fetchers_;
 
   base::Lock shared_memory_lock_;
   std::unique_ptr<GamepadSharedBuffer> gamepad_shared_buffer_;
@@ -165,8 +221,6 @@ class DEVICE_GAMEPAD_EXPORT GamepadProvider
 
   GamepadConnectionChangeClient* connection_change_client_;
 
-  static GamepadProvider* instance_;
-
   DISALLOW_COPY_AND_ASSIGN(GamepadProvider);
 };