Add GRALLOC_USAGE_HW_COMPOSER usage flag to preview streams

This CL adds GRALLOC_USAGE_HW_COMPOSER usage flag to preview streams. In
Chrome Camera App (CCA), we set the format of preview stream to be
HAL_PIXEL_FORMAT_YCBCR_420_888, which is identical to the format used by
portrait mode. We need an additional usage for HAL to differentiate the
streams.

BUG=None
TEST=Recompiled and redeployed Chrome and verified the usage flag in HAL
adapter.

Change-Id: I2b6002e87f2539ca9338af84aa0daa4927575235
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635123
Auto-Submit: Jasmine Chen <lnishan@google.com>
Commit-Queue: Jasmine Chen <lnishan@google.com>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#667861}

media/capture/video/chromeos/camera_device_delegate.cc

@@ -545,6 +545,7 @@ void CameraDeviceDelegate::ConfigureStreams(
       chrome_capture_params_.requested_format.frame_size.height();
   preview_stream->format =
       cros::mojom::HalPixelFormat::HAL_PIXEL_FORMAT_YCbCr_420_888;
+  preview_stream->usage = cros::mojom::GRALLOC_USAGE_HW_COMPOSER;
   preview_stream->data_space = 0;
   preview_stream->rotation =
       cros::mojom::Camera3StreamRotation::CAMERA3_STREAM_ROTATION_0;

media/capture/video/chromeos/mojo/camera3.mojom

@@ -8,6 +8,17 @@ module cros.mojom;
 
 import "media/capture/video/chromeos/mojo/camera_metadata.mojom";
 
+// These usages flags are defined in gralloc.h. They determine the nature of
+// the buffers allocated by gralloc. Read more on:
+// https://source.android.com/devices/graphics/arch-bq-gralloc#gralloc_HAL
+const uint32 GRALLOC_USAGE_SW_READ_NEVER = 0x00000000;
+const uint32 GRALLOC_USAGE_SW_READ_OFTEN = 0x00000003;
+const uint32 GRALLOC_USAGE_SW_WRITE_NEVER = 0x00000000;
+const uint32 GRALLOC_USAGE_SW_WRITE_OFTEN = 0x00000030;
+const uint32 GRALLOC_USAGE_HW_COMPOSER = 0x00000800;
+const uint32 GRALLOC_USAGE_HW_CAMERA_WRITE = 0x00020000;
+const uint32 GRALLOC_USAGE_HW_CAMERA_READ = 0x00040000;
+
 [Extensible]
 enum HalPixelFormat {
   HAL_PIXEL_FORMAT_RGBA_8888 = 0x1,
@@ -56,6 +67,10 @@ struct Camera3Stream {
   uint32 width;
   uint32 height;
   HalPixelFormat format;
+  // usage stores the gralloc usage flags for this stream and determines the
+  // nature of it. The value is used by Chrome VCD, Android framework and camera
+  // HAL. Read more on:
+  // https://source.android.com/devices/graphics/arch-bq-gralloc#gralloc_HAL
   uint32 usage;
   uint32 max_buffers;
   uint32 data_space;