Add support for compressed GPU memory buffers.

content/common/gpu/client/gpu_memory_buffer_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/common/gpu/client/gpu_memory_buffer_impl.h"
 
 #include "base/logging.h"
 #include "base/numerics/safe_math.h"
 #include "content/common/gpu/client/gpu_memory_buffer_impl_shared_memory.h"
 #include "ui/gl/gl_bindings.h"
@@ skipping 64 matching lines @@
     ClientBuffer buffer) {
   return reinterpret_cast<GpuMemoryBufferImpl*>(buffer);
 }
 
 // static
 bool GpuMemoryBufferImpl::StrideInBytes(size_t width,
                                         Format format,
                                         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:
       s *= 4;
       if (!s.IsValid())
         return false;
 
       *stride_in_bytes = s.ValueOrDie();
       return true;
   }
 
   NOTREACHED();
   return false;
 }
 
 gfx::GpuMemoryBuffer::Format GpuMemoryBufferImpl::GetFormat() const {
   return format_;
 }
 
 bool GpuMemoryBufferImpl::IsMapped() const {
   return mapped_;
 }
 
 ClientBuffer GpuMemoryBufferImpl::AsClientBuffer() {
   return reinterpret_cast<ClientBuffer>(this);
 }
 
 }  // namespace content