vaapi cleanup: a few s/const/constexpr/

This CL s/const/constexpr/ in a few locations in vaapi/ folder.
No new code intended, just that substitution.

TBR=dcastagna@chromium.org

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I4ec733806feff58a70e8e9ab1c0d7f4565f1733c
Reviewed-on: https://chromium-review.googlesource.com/1012949
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551403}

media/gpu/vaapi/vaapi_h264_accelerator.cc

@@ -24,12 +24,12 @@ namespace {
 // from ITU-T REC H.264 spec
 // section 8.5.6
 // "Inverse scanning process for 4x4 transform coefficients and scaling lists"
-static const int kZigzagScan4x4[16] = {0, 1,  4,  8,  5, 2,  3,  6,
+static constexpr int kZigzagScan4x4[16] = {0, 1,  4,  8,  5, 2,  3,  6,
                                            9, 12, 13, 10, 7, 11, 14, 15};
 
 // section 8.5.7
 // "Inverse scanning process for 8x8 transform coefficients and scaling lists"
-static const uint8_t kZigzagScan8x8[64] = {
+static constexpr uint8_t kZigzagScan8x8[64] = {
     0,  1,  8,  16, 9,  2,  3,  10, 17, 24, 32, 25, 18, 11, 4,  5,
     12, 19, 26, 33, 40, 48, 41, 34, 27, 20, 13, 6,  7,  14, 21, 28,
     35, 42, 49, 56, 57, 50, 43, 36, 29, 22, 15, 23, 30, 37, 44, 51,

media/gpu/vaapi/vaapi_jpeg_decoder_unittest.cc

@@ -26,8 +26,8 @@
 namespace media {
 namespace {
 
-const char* kTestFilename = "pixel-1280x720.jpg";
-const char* kExpectedMd5Sum = "6e9e1716073c9a9a1282e3f0e0dab743";
+constexpr char* kTestFilename = "pixel-1280x720.jpg";
+constexpr char* kExpectedMd5Sum = "6e9e1716073c9a9a1282e3f0e0dab743";
 
 void LogOnError() {
   LOG(FATAL) << "Oh noes! Decoder failed";

media/gpu/vaapi/vaapi_jpeg_encode_accelerator.cc

@@ -30,7 +30,7 @@ namespace {
 // JPEG format uses 2 bytes to denote the size of a segment, and the size
 // includes the 2 bytes used for specifying it. Therefore, maximum data size
 // allowed is: 65535 - 2 = 65533.
-const size_t kMaxExifSizeAllowed = 65533;
+constexpr size_t kMaxExifSizeAllowed = 65533;
 
 // UMA results that the VaapiJpegEncodeAccelerator class reports.
 // These values are persisted to logs, and should therefore never be renumbered

media/gpu/vaapi/vaapi_jpeg_encoder.cc

@@ -26,25 +26,25 @@ namespace media {
 namespace {
 
 // JPEG header only uses 2 bytes to represent width and height.
-const int kMaxDimension = 65535;
-const size_t kDctSize2 = 64;
-const size_t kNumDcRunSizeBits = 16;
-const size_t kNumAcRunSizeBits = 16;
-const size_t kNumDcCodeWordsHuffVal = 12;
-const size_t kNumAcCodeWordsHuffVal = 162;
-const size_t kJpegDefaultHeaderSize =
+constexpr int kMaxDimension = 65535;
+constexpr size_t kDctSize2 = 64;
+constexpr size_t kNumDcRunSizeBits = 16;
+constexpr size_t kNumAcRunSizeBits = 16;
+constexpr size_t kNumDcCodeWordsHuffVal = 12;
+constexpr size_t kNumAcCodeWordsHuffVal = 162;
+constexpr size_t kJpegDefaultHeaderSize =
     67 + (kDctSize2 * 2) + (kNumDcRunSizeBits * 2) +
     (kNumDcCodeWordsHuffVal * 2) + (kNumAcRunSizeBits * 2) +
     (kNumAcCodeWordsHuffVal * 2);
-const size_t kJFIFApp0Size = 16;
+constexpr size_t kJFIFApp0Size = 16;
 
-const uint8_t kZigZag8x8[64] = {
+constexpr uint8_t kZigZag8x8[64] = {
     0,  1,  8,  16, 9,  2,  3,  10, 17, 24, 32, 25, 18, 11, 4,  5,
     12, 19, 26, 33, 40, 48, 41, 34, 27, 20, 13, 6,  7,  14, 21, 28,
     35, 42, 49, 56, 57, 50, 43, 36, 29, 22, 15, 23, 30, 37, 44, 51,
     58, 59, 52, 45, 38, 31, 39, 46, 53, 60, 61, 54, 47, 55, 62, 63};
 
-const JpegQuantizationTable kDefaultQuantTable[2] = {
+constexpr JpegQuantizationTable kDefaultQuantTable[2] = {
     // Table K.1 Luminance quantization table values.
     {
         true,

media/gpu/vaapi/vaapi_video_encode_accelerator.cc

@@ -39,14 +39,14 @@ namespace media {
 namespace {
 // Need 2 surfaces for each frame: one for input data and one for
 // reconstructed picture, which is later used for reference.
-const size_t kMinSurfacesToEncode = 2;
+constexpr size_t kMinSurfacesToEncode = 2;
 
 // Subjectively chosen.
-const size_t kNumInputBuffers = 4;
-const size_t kMaxNumReferenceFrames = 4;
+constexpr size_t kNumInputBuffers = 4;
+constexpr size_t kMaxNumReferenceFrames = 4;
 
 // TODO(owenlin): Adjust the value after b/71367113 is fixed
-const size_t kExtraOutputBufferSize = 32768;  // bytes
+constexpr size_t kExtraOutputBufferSize = 32768;  // bytes
 
 // We need up to kMaxNumReferenceFrames surfaces for reference, plus one
 // for input and one for encode (which will be added to the set of reference
@@ -56,28 +56,28 @@ const size_t kExtraOutputBufferSize = 32768;  // bytes
 // encode surfaces (i.e. kMaxNumReferenceFrames + kMinSurfacesToEncode), and
 // (kNumInputBuffers - 1) of kMinSurfacesToEncode for the remaining frames
 // in flight.
-const size_t kNumSurfaces = kMaxNumReferenceFrames + kMinSurfacesToEncode +
+constexpr size_t kNumSurfaces = kMaxNumReferenceFrames + kMinSurfacesToEncode +
                                 kMinSurfacesToEncode * (kNumInputBuffers - 1);
 
 // An IDR every 2048 frames, an I frame every 256 and no B frames.
 // We choose IDR period to equal MaxFrameNum so it must be a power of 2.
-const int kIDRPeriod = 2048;
-const int kIPeriod = 256;
-const int kIPPeriod = 1;
+constexpr int kIDRPeriod = 2048;
+constexpr int kIPeriod = 256;
+constexpr int kIPPeriod = 1;
 
-const int kDefaultFramerate = 30;
+constexpr int kDefaultFramerate = 30;
 
 // HRD parameters (ch. E.2.2 in spec).
-const int kBitRateScale = 0;  // bit_rate_scale for SPS HRD parameters.
-const int kCPBSizeScale = 0;  // cpb_size_scale for SPS HRD parameters.
+constexpr int kBitRateScale = 0;  // bit_rate_scale for SPS HRD parameters.
+constexpr int kCPBSizeScale = 0;  // cpb_size_scale for SPS HRD parameters.
 
-const int kDefaultQP = 26;
+constexpr int kDefaultQP = 26;
 // All Intel codecs can do at least 4.1.
-const int kDefaultLevelIDC = 41;
-const int kChromaFormatIDC = 1;  // 4:2:0
+constexpr int kDefaultLevelIDC = 41;
+constexpr int kChromaFormatIDC = 1;  // 4:2:0
 
 // Arbitrarily chosen bitrate window size for rate control, in ms.
-const int kCPBWindowSizeMs = 1500;
+constexpr int kCPBWindowSizeMs = 1500;
 
 // UMA errors that the VaapiVideoEncodeAccelerator class reports.
 enum VAVEAEncoderFailure {

media/gpu/vaapi/vaapi_wrapper.cc

@@ -124,7 +124,7 @@ namespace {
 
 // Maximum framerate of encoded profile. This value is an arbitary limit
 // and not taken from HW documentation.
-const int kMaxEncoderFramerate = 30;
+constexpr int kMaxEncoderFramerate = 30;
 
 // A map between VideoCodecProfile and VAProfile.
 static const struct {