Add YUV_420_BIPLANAR as a supported GMB configuration on Mac.

content/common/gpu/client/gpu_memory_buffer_impl_io_surface.cc

Index: content/common/gpu/client/gpu_memory_buffer_impl_io_surface.cc
diff --git a/content/common/gpu/client/gpu_memory_buffer_impl_io_surface.cc b/content/common/gpu/client/gpu_memory_buffer_impl_io_surface.cc
index f16125bfa181f8e5bd51abfe54c0d48b3d453511..4cf13dcc65964f07c78c3ae1a5fdd9a16c9a81ff 100644
--- a/content/common/gpu/client/gpu_memory_buffer_impl_io_surface.cc
+++ b/content/common/gpu/client/gpu_memory_buffer_impl_io_surface.cc
@@ -61,7 +61,14 @@ bool GpuMemoryBufferImplIOSurface::Map(void** data) {
   IOReturn status = IOSurfaceLock(io_surface_, lock_flags_, NULL);
   DCHECK_NE(status, kIOReturnCannotLock);
   mapped_ = true;
-  *data = IOSurfaceGetBaseAddress(io_surface_);
+
+  const size_t planes = IOSurfaceGetPlaneCount(io_surface_);
+  if (planes == 0) {
+    data[0] = IOSurfaceGetBaseAddress(io_surface_);
+  } else {
+    for (size_t plane = 0; plane < planes; ++plane)
+      data[plane] = IOSurfaceGetBaseAddressOfPlane(io_surface_, plane);
+  }
   return true;
 }
 
@@ -71,8 +78,14 @@ void GpuMemoryBufferImplIOSurface::Unmap() {
   mapped_ = false;
 }
 
-void GpuMemoryBufferImplIOSurface::GetStride(int* stride) const {
-  *stride = IOSurfaceGetBytesPerRow(io_surface_);
+void GpuMemoryBufferImplIOSurface::GetStride(int* strides) const {
+  const size_t planes = IOSurfaceGetPlaneCount(io_surface_);
+  if (planes == 0) {
+    strides[0] = IOSurfaceGetBytesPerRow(io_surface_);
+  } else {
+    for (size_t plane = 0; plane < planes; ++plane)
+      strides[plane] = IOSurfaceGetBytesPerRowOfPlane(io_surface_, plane);
+  }
 }
 
 gfx::GpuMemoryBufferHandle GpuMemoryBufferImplIOSurface::GetHandle() const {