capture/replay: implement CaptureGetTexImageANGLE_pixels

src/libANGLE/capture/capture_gles_ext_params.cpp

@@ -3402,7 +3402,22 @@ void CaptureGetTexImageANGLE_pixels(const State &glState,
                                     void *pixels,
                                     angle::ParamCapture *paramCapture)
 {
-    UNIMPLEMENTED();
+    if (glState.getTargetBuffer(gl::BufferBinding::PixelPack))
+    {
+        // If a pixel pack buffer is bound, this is an offset, not a pointer
+        paramCapture->value.voidPointerVal = pixels;
+        return;
+    }
+
+    const Texture *texture = glState.getTargetTexture(TextureTargetToType(target));
+    ASSERT(texture);
+
+    // Use a conservative upper bound instead of an exact size to be simple.
+    static constexpr GLsizei kMaxPixelSize = 32;
+    size_t width                           = texture->getWidth(target, level);
+    size_t height                          = texture->getHeight(target, level);
+    size_t depth                           = texture->getDepth(target, level);
+    paramCapture->readBufferSizeBytes      = kMaxPixelSize * width * height * depth;
 }
 
 void CaptureGetRenderbufferImageANGLE_pixels(const State &glState,