Added support for GVR controllers

device/vr/android/gvr/gvr_gamepad_data_fetcher.cc

Index: device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
diff --git a/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc b/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e7da5e1a951cafa6f30d1c5d62ef73a8f7ac4c13
--- /dev/null
+++ b/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
@@ -0,0 +1,124 @@
+// 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 "device/vr/android/gvr/gvr_gamepad_data_fetcher.h"
+
+#include "base/strings/utf_string_conversions.h"
+
+#include "device/vr/android/gvr/gvr_delegate.h"
+#include "third_party/WebKit/public/platform/WebGamepads.h"
+
+namespace device {
+
+namespace {
+
+void CopyToWebUString(unsigned short* dest,
+                      size_t dest_length,
+                      base::string16 src) {
+  const size_t str_to_copy = std::min(src.size(), dest_length - 1);
+  memcpy(dest, src.data(), str_to_copy * sizeof(base::string16::value_type));
+  dest[str_to_copy] = 0;
+}
+
+}  // namespace
+
+using namespace blink;
+
+GvrGamepadDataFetcher::Factory::Factory(GvrDelegate* delegate)
+    : delegate_(delegate) {}
+
+GvrGamepadDataFetcher::Factory::~Factory() {}
+
+std::unique_ptr<GamepadDataFetcher>
+GvrGamepadDataFetcher::Factory::CreateDataFetcher() {
+  return std::unique_ptr<GamepadDataFetcher>(
+      new GvrGamepadDataFetcher(delegate_));
+}
+
+GamepadSource GvrGamepadDataFetcher::Factory::source() {
+  return GAMEPAD_SOURCE_GVR;
+}
+
+GvrGamepadDataFetcher::GvrGamepadDataFetcher(GvrDelegate* delegate) {
+  gvr::GvrApi* gvr_api = delegate->gvr_api();
+  controller_api_.reset(new gvr::ControllerApi());
+  int32_t options = gvr::ControllerApi::DefaultOptions();
+  options |= GVR_CONTROLLER_ENABLE_GYRO;
+  bool success = controller_api_->Init(options, gvr_api->GetContext());
+  if (!success)
+    controller_api_.reset(nullptr);
+}
+
+GvrGamepadDataFetcher::~GvrGamepadDataFetcher() {}
+
+GamepadSource GvrGamepadDataFetcher::source() {
+  return GAMEPAD_SOURCE_GVR;
+}
+
+void GvrGamepadDataFetcher::OnAddedToProvider() {
+  PauseHint(false);
+}
+
+void GvrGamepadDataFetcher::GetGamepadData(bool devices_changed_hint) {
+  if (!controller_api_)
+    return;
+
+  PadState* state = GetPadState(0);
+  if (!state)
+    return;
+
+  WebGamepad& pad = state->data;

[mthiesse, 2016/09/18 23:21:48]

Just to check my understanding, we're only exposing the touch pad and
orientation right? The other buttons are controlled by the system, or by
VrShell?

+  if (state->active_state == GAMEPAD_NEWLY_ACTIVE) {
+    // This is the first time we've seen this device, so do some one-time
+    // initialization
+    pad.connected = true;
+    CopyToWebUString(pad.id, WebGamepad::idLengthCap,

[mthiesse, 2016/09/18 23:21:48]

Should this be WebGamepad::idLengthCap + 1 to include the null termination?

Upon searching I think your use of the value matches other uses of this value...


In your CL https://codereview.chromium.org/2300543003 where you update
WebGamepad.h, could you add a comment or something explaining that the
idLengthCap and mappingLengthCap include the null termination (hence the actual
length cap for the ID is one character less (the null termination is an artifact
of how the data is stored))? It's especially confusing because the other length
caps are for non-null-terminated data.

+                     base::UTF8ToUTF16("Daydream Controller"));
+    CopyToWebUString(pad.mapping, WebGamepad::mappingLengthCap,
+                     base::UTF8ToUTF16(""));
+    pad.buttonsLength = 1;
+    pad.axesLength = 2;
+  }
+
+  controller_state_.Update(*controller_api_);
+
+  pad.timestamp = controller_state_.GetLastOrientationTimestamp();
+
+  pad.hand = GamepadHandRight;
+
+  gvr_vec2f touch_position = controller_state_.GetTouchPos();
+  pad.axes[0] = (touch_position.x * 2.0) - 1.0;
+  pad.axes[1] = (touch_position.y * 2.0) - 1.0;
+
+  // TODO: use gamepad touched attribute to communicate touched state
+  pad.buttons[0].touched = controller_state_.IsTouching();
+  pad.buttons[0].pressed =
+      controller_state_.GetButtonState(GVR_CONTROLLER_BUTTON_CLICK);
+  pad.buttons[0].value = pad.buttons[0].pressed ? 1.0f : 0.0f;
+
+  // TODO: expose orientation/acceleration/velocity

[mthiesse, 2016/09/18 23:21:48]

Should orientation still be in this TODO? Looks like it's being exposed.

+  pad.pose.notNull = true;
+  pad.pose.hasOrientation = true;
+  pad.pose.hasPosition = false;
+
+  gvr_quatf orientation = controller_state_.GetOrientation();
+  pad.pose.orientation.notNull = true;
+  pad.pose.orientation.x = orientation.qx;
+  pad.pose.orientation.y = orientation.qy;
+  pad.pose.orientation.z = orientation.qz;
+  pad.pose.orientation.w = orientation.qw;
+}
+
+void GvrGamepadDataFetcher::PauseHint(bool paused) {
+  if (!controller_api_)
+    return;
+
+  if (paused) {
+    controller_api_->Pause();
+  } else {
+    controller_api_->Resume();
+  }
+}
+
+}  // namespace device