Merge: Fix concurrency issue in DataFetcherImplAndroid.

This is a partial merge from https://codereview.chromium.org/55143008/.
This patch adds a lock to protect device_motion_buffer_ from
concurrent modification by 2 separate threads.

We don't need a lock for device_orientation_buffer_ because
in M31 Device Orientation API still uses the old implementation
without shared memory and therefore does not require locking.

BUG=313457
NOTRY=true
R=mvanouwerkerk@chromium.org

Review URL: https://codereview.chromium.org/59733002

git-svn-id: svn://svn.chromium.org/chrome/branches/1650/src@233004 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 32 insertions, 6 deletions

diff --git a/content/browser/device_orientation/data_fetcher_impl_android.cc b/content/browser/device_orientation/data_fetcher_impl_android.cc
index d2f6016..8d4919c 100644
--- a/content/browser/device_orientation/data_fetcher_impl_android.cc
+++ b/content/browser/device_orientation/data_fetcher_impl_android.cc
@@ -98,6 +98,11 @@ void DataFetcherImplAndroid::GotOrientation(
 
 void DataFetcherImplAndroid::GotAcceleration(
     JNIEnv*, jobject, double x, double y, double z) {
+  base::AutoLock autolock(motion_buffer_lock_);
+
+  if (!device_motion_buffer_)
+    return;
+
   device_motion_buffer_->seqlock.WriteBegin();
   device_motion_buffer_->data.accelerationX = x;
   device_motion_buffer_->data.hasAccelerationX = true;
@@ -115,6 +120,11 @@ void DataFetcherImplAndroid::GotAcceleration(
 
 void DataFetcherImplAndroid::GotAccelerationIncludingGravity(
     JNIEnv*, jobject, double x, double y, double z) {
+  base::AutoLock autolock(motion_buffer_lock_);
+
+  if (!device_motion_buffer_)
+    return;
+
   device_motion_buffer_->seqlock.WriteBegin();
   device_motion_buffer_->data.accelerationIncludingGravityX = x;
   device_motion_buffer_->data.hasAccelerationIncludingGravityX = true;
@@ -132,6 +142,11 @@ void DataFetcherImplAndroid::GotAccelerationIncludingGravity(
 
 void DataFetcherImplAndroid::GotRotationRate(
     JNIEnv*, jobject, double alpha, double beta, double gamma) {
+  base::AutoLock autolock(motion_buffer_lock_);
+
+  if (!device_motion_buffer_)
+    return;
+
   device_motion_buffer_->seqlock.WriteBegin();
   device_motion_buffer_->data.rotationRateAlpha = alpha;
   device_motion_buffer_->data.hasRotationRateAlpha = true;
@@ -176,23 +191,32 @@ int DataFetcherImplAndroid::GetNumberActiveDeviceMotionSensors() {
 bool DataFetcherImplAndroid::StartFetchingDeviceMotionData(
     DeviceMotionHardwareBuffer* buffer) {
   DCHECK(buffer);
-  device_motion_buffer_ = buffer;
-  ClearInternalMotionBuffers();
+  {
+    base::AutoLock autolock(motion_buffer_lock_);
+    device_motion_buffer_ = buffer;
+    ClearInternalMotionBuffers();
+  }
   bool success = Start(DeviceData::kTypeMotion);
 
   // If no motion data can ever be provided, the number of active device motion
   // sensors will be zero. In that case flag the shared memory buffer
   // as ready to read, as it will not change anyway.
   number_active_device_motion_sensors_ = GetNumberActiveDeviceMotionSensors();
-  CheckMotionBufferReadyToRead();
+  {
+    base::AutoLock autolock(motion_buffer_lock_);
+    CheckMotionBufferReadyToRead();
+  }
   return success;
 }
 
 void DataFetcherImplAndroid::StopFetchingDeviceMotionData() {
   Stop(DeviceData::kTypeMotion);
-  if (device_motion_buffer_) {
-    ClearInternalMotionBuffers();
-    device_motion_buffer_ = NULL;
+  {
+    base::AutoLock autolock(motion_buffer_lock_);
+    if (device_motion_buffer_) {
+      ClearInternalMotionBuffers();
+      device_motion_buffer_ = NULL;
+    }
   }
 }
 
diff --git a/content/browser/device_orientation/data_fetcher_impl_android.h b/content/browser/device_orientation/data_fetcher_impl_android.h
index 35ed1c7..f348e1d 100644
--- a/content/browser/device_orientation/data_fetcher_impl_android.h
+++ b/content/browser/device_orientation/data_fetcher_impl_android.h
@@ -99,6 +99,8 @@ class CONTENT_EXPORT DataFetcherImplAndroid {
   bool is_motion_buffer_ready_;
   bool is_orientation_buffer_ready_;
 
+  base::Lock motion_buffer_lock_;
+
   DISALLOW_COPY_AND_ASSIGN(DataFetcherImplAndroid);
 };