Enable sampling from DXGI NV12 formats in GLRenderer.

cc/resources/video_resource_updater.cc

Index: cc/resources/video_resource_updater.cc
diff --git a/cc/resources/video_resource_updater.cc b/cc/resources/video_resource_updater.cc
index e77cd7505af1c58cecfbfe1f07bb0d32f9641a01..facae16223181d59fb1b4863025f4f87cd418d09 100644
--- a/cc/resources/video_resource_updater.cc
+++ b/cc/resources/video_resource_updater.cc
@@ -346,6 +346,12 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
   for (size_t i = 0; i < output_plane_count; ++i) {
     gfx::Size output_plane_resource_size =
         SoftwarePlaneDimension(video_frame.get(), software_compositor, i);
+    ResourceFormat plane_resource_format = output_resource_format;
+    if ((input_frame_format == media::PIXEL_FORMAT_NV12) && (i == 1)) {

[danakj, 2016/04/13 00:24:18]

If all of this is for tests I'd prefer to just not support NV12 here at all. Is
that the case?

I was thinking of these tests:
https://code.google.com/p/chromium/codesearch#chromium/src/cc/output/gl_rende...

Are the pixel tests testing more production code than that would?

+      // A two-byte-per-pixel format would avoid wasting space, but this is
+      // only used in testing.
+      plane_resource_format = RGBA_8888;
+    }
     if (output_plane_resource_size.IsEmpty() ||
         output_plane_resource_size.width() > max_resource_size ||
         output_plane_resource_size.height() > max_resource_size) {
@@ -356,7 +362,7 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
     ResourceList::iterator resource_it = all_resources_.end();
     for (auto it = all_resources_.begin(); it != all_resources_.end(); ++it) {
       if (it->resource_size == output_plane_resource_size &&
-          it->resource_format == output_resource_format) {
+          it->resource_format == plane_resource_format) {
         if (PlaneResourceMatchesUniqueID(*it, video_frame.get(), i)) {
           // Bingo, we found a resource that already contains the data we are
           // planning to put in it. It's safe to reuse it even if
@@ -383,7 +389,7 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
     if (resource_it == all_resources_.end()) {
       const bool is_immutable = true;
       resource_it =
-          AllocateResource(output_plane_resource_size, output_resource_format,
+          AllocateResource(output_plane_resource_size, plane_resource_format,
                            !software_compositor, is_immutable);
     }
     if (resource_it == all_resources_.end())
@@ -440,9 +446,6 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
   for (size_t i = 0; i < plane_resources.size(); ++i) {
     PlaneResource& plane_resource = *plane_resources[i];
     // Update each plane's resource id with its content.
-    DCHECK_EQ(plane_resource.resource_format,
-              resource_provider_->YuvResourceFormat(bits_per_channel));
-
     if (!PlaneResourceMatchesUniqueID(plane_resource, video_frame.get(), i)) {
       // We need to transfer data from |video_frame| to the plane resource.
       // TODO(reveman): Can use GpuMemoryBuffers here to improve performance.
@@ -463,6 +466,7 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
 
       bool needs_conversion = false;
       int shift = 0;
+      bool needs_expansion = false;
 
       // LUMINANCE_F16 uses half-floats, so we always need a conversion step.
       if (plane_resource.resource_format == LUMINANCE_F16) {
@@ -475,6 +479,11 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
         // shift the data down and create an 8-bit texture.
         needs_conversion = true;
         shift = bits_per_channel - 8;
+      } else if ((input_frame_format == media::PIXEL_FORMAT_NV12) && (i == 1)) {
+        DCHECK_EQ(RGBA_8888, plane_resource.resource_format);
+        needs_conversion = true;
+        // Expand each 2 byte pixel into 4 bytes.
+        needs_expansion = true;
       }
       const uint8_t* pixels;
       if (static_cast<int>(upload_image_stride) == video_stride_bytes &&
@@ -508,6 +517,16 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
                 video_frame->data(i) + (video_stride_bytes * row));
             for (size_t i = 0; i < bytes_per_row; i++)
               dst[i] = src[i] >> shift;
+          } else if (needs_expansion) {
+            uint32_t* dst = reinterpret_cast<uint32_t*>(
+                &upload_pixels_[upload_image_stride * row]);
+            const uint8_t* src =
+                video_frame->data(i) + (video_stride_bytes * row);
+            for (size_t i = 0; i < bytes_per_row / 4; i++) {
+              // The first channel (U) goes in the R component, and the second
+              // (V) goes in the G component. B and A are black.
+              dst[i] = ((src[i * 2] << 24) | (src[i * 2 + 1] << 16));
+            }
           } else {
             // Input and output are the same size and format, but
             // differ in stride, copy one row at a time.