Add support for compressed GPU memory buffers.

content/common/gpu/client/gpu_memory_buffer_impl.cc

Index: content/common/gpu/client/gpu_memory_buffer_impl.cc
diff --git a/content/common/gpu/client/gpu_memory_buffer_impl.cc b/content/common/gpu/client/gpu_memory_buffer_impl.cc
index 4b05bbff2aa1c4ce67da55713b3d020a4a9d8f0a..0c0426f6794c394c3c05ad6abebdf1ace85f611b 100644
--- a/content/common/gpu/client/gpu_memory_buffer_impl.cc
+++ b/content/common/gpu/client/gpu_memory_buffer_impl.cc
@@ -82,6 +82,20 @@ bool GpuMemoryBufferImpl::StrideInBytes(size_t width,
                                         size_t* stride_in_bytes) {
   base::CheckedNumeric<size_t> s = width;
   switch (format) {
+    case ATCIA:
+    case DXT5:
+      *stride_in_bytes = width;
+      return true;
+    case ATC:
+    case DXT1:
+    case ETC1:
+      DCHECK_EQ(width % 2, 0U);

[piman, 2015/02/19 23:52:04]

Could we add a DCHECK, somewhere on the client side (the constructor?), that the
size is valid? E.g. by sharing that ValidSize function.
It's easier to find the root cause of errors on the client side with a DCHEKC
than on the service side with a logged message. WDYT?

[christiank, 2015/02/20 08:32:14]

I agree, sounds like a good idea. Fixed.

+      s /= 2;
+      if (!s.IsValid())
+        return false;
+
+      *stride_in_bytes = s.ValueOrDie();
+      return true;
     case RGBA_8888:
     case RGBX_8888:
     case BGRA_8888: