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 "base/numerics/safe_math.h"
 #include "content/common/gpu/client/gpu_memory_buffer_impl_shared_memory.h"
 #include "ui/gl/gl_bindings.h"
 
 #if defined(OS_MACOSX)
 #include "content/common/gpu/client/gpu_memory_buffer_impl_io_surface.h"
 #endif
 
 #if defined(OS_ANDROID)
 #include "content/common/gpu/client/gpu_memory_buffer_impl_surface_texture.h"
 #endif
@@ skipping 51 matching lines @@
   }
 }
 
 // static
 GpuMemoryBufferImpl* GpuMemoryBufferImpl::FromClientBuffer(
     ClientBuffer buffer) {
   return reinterpret_cast<GpuMemoryBufferImpl*>(buffer);
 }
 
 // static
-size_t GpuMemoryBufferImpl::BytesPerPixel(Format format) {
+bool GpuMemoryBufferImpl::StrideInBytes(size_t width,
+                                        Format format,
+                                        size_t* stride_in_bytes) {
+  base::CheckedNumeric<size_t> w = width;

[reveman, 2015/01/13 16:04:40]

nit: maybe s/w/s/ for stride

   switch (format) {
     case RGBA_8888:
     case RGBX_8888:
     case BGRA_8888:
-      return 4;
+      w *= 4;
+      break;
+    default:

[reveman, 2015/01/13 16:04:40]

nit: please avoid having a default case as that allows the compiler to help
ensure we update this code after adding new formats. it's still nice to have the
NOTREACHED outside the switch statement in case format is somehow messed up at
runtime. maybe just keep this as before for now and put the IsValid check inside
the switch statement..

+      NOTREACHED();
+      return false;
   }
 
-  NOTREACHED();
-  return 0;
+  if (!w.IsValid())
+    return false;
+
+  *stride_in_bytes = w.ValueOrDie();
+  return true;
 }
 
 gfx::GpuMemoryBuffer::Format GpuMemoryBufferImpl::GetFormat() const {
   return format_;
 }
 
 bool GpuMemoryBufferImpl::IsMapped() const {
   return mapped_;
 }
 
 ClientBuffer GpuMemoryBufferImpl::AsClientBuffer() {
   return reinterpret_cast<ClientBuffer>(this);
 }
 
 }  // namespace content