Update GPU memory buffers to use StrideInBytes internally.

ui/gl/gl_image_memory.cc

 // Copyright 2014 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 "ui/gl/gl_image_memory.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/scoped_binders.h"
@@ skipping 82 matching lines @@
 
 GLImageMemory::~GLImageMemory() {
 #if defined(OS_WIN) || defined(USE_X11) || defined(OS_ANDROID) || \
     defined(USE_OZONE)
   DCHECK_EQ(EGL_NO_IMAGE_KHR, egl_image_);
   DCHECK_EQ(0u, egl_texture_id_);
 #endif
 }
 
 // static
-size_t GLImageMemory::BytesPerPixel(gfx::GpuMemoryBuffer::Format format) {
+bool GLImageMemory::StrideInBytes(size_t width,
+                                  gfx::GpuMemoryBuffer::Format format,
+                                  size_t* stride_in_bytes) {
+  base::CheckedNumeric<size_t> w = width;

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

nit: s/w/s/ for stride?

   switch (format) {
     case gfx::GpuMemoryBuffer::RGBA_8888:
     case gfx::GpuMemoryBuffer::BGRA_8888:
-      return 4;
+      w *= 4;
+      break;
     case gfx::GpuMemoryBuffer::RGBX_8888:
       NOTREACHED();
-      return 0;
+      return false;
   }
 
-  NOTREACHED();
-  return 0;
+  if (!w.IsValid())
+    return false;
+
+  *stride_in_bytes = w.ValueOrDie();
+  return true;

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

nit: would be nice to have a NOTREACHED check here in case format is an invalid
value at runtime. maybe move this IsValid code up into the switch statement?

 }
 
 bool GLImageMemory::Initialize(const unsigned char* memory,
                                gfx::GpuMemoryBuffer::Format format) {
   if (!ValidInternalFormat(internalformat_)) {
     LOG(ERROR) << "Invalid internalformat: " << internalformat_;
     return false;
   }
 
   if (!ValidFormat(format)) {
@@ skipping 155 matching lines @@
                TextureFormat(format_),
                size_.width(),
                size_.height(),
                0,  // border
                DataFormat(format_),
                DataType(format_),
                memory_);
 }
 
 }  // namespace gfx