Update GPU memory buffers to use StrideInBytes internally.

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 "content/common/gpu/client/gpu_memory_buffer_impl_shared_memory.h"
 #include "ui/gl/gl_bindings.h"
 
@@ skipping 58 matching lines @@
   }
 }
 
 // static
 GpuMemoryBufferImpl* GpuMemoryBufferImpl::FromClientBuffer(
     ClientBuffer buffer) {
   return reinterpret_cast<GpuMemoryBufferImpl*>(buffer);
 }
 
 // static
-size_t GpuMemoryBufferImpl::BytesPerPixel(Format format) {
+size_t GpuMemoryBufferImpl::BitsPerPixel(Format format) {
   switch (format) {
     case RGBA_8888:
     case RGBX_8888:
     case BGRA_8888:
-      return 4;
+      return 32;
   }
 
   NOTREACHED();
   return 0;
 }
 
+// static
+size_t GpuMemoryBufferImpl::PixelsToBytes(
+    size_t pixel_count,
+    gfx::GpuMemoryBuffer::Format format) {
+  size_t size_in_bits = pixel_count * BitsPerPixel(format);
+  DCHECK_EQ(size_in_bits % 8, 0u);
+  return size_in_bits / 8;
+}
+
 gfx::GpuMemoryBuffer::Format GpuMemoryBufferImpl::GetFormat() const {
   return format_;
 }
 
 bool GpuMemoryBufferImpl::IsMapped() const {
   return mapped_;
 }
 
 ClientBuffer GpuMemoryBufferImpl::AsClientBuffer() {
   return reinterpret_cast<ClientBuffer>(this);
 }
 
 }  // namespace content