Update GPU memory buffers to use StrideInBytes internally.

cc/test/test_gpu_memory_buffer_manager.cc

Index: cc/test/test_gpu_memory_buffer_manager.cc
diff --git a/cc/test/test_gpu_memory_buffer_manager.cc b/cc/test/test_gpu_memory_buffer_manager.cc
index 3583ff30da7093beaf9af8a7f2fd444e15abd04b..150c4d88222fef8c0fe0f42af98e9a656d1c3abb 100644
--- a/cc/test/test_gpu_memory_buffer_manager.cc
+++ b/cc/test/test_gpu_memory_buffer_manager.cc
@@ -10,18 +10,24 @@
 namespace cc {
 namespace {
 
-size_t BytesPerPixel(gfx::GpuMemoryBuffer::Format format) {
+size_t BitsPerPixel(gfx::GpuMemoryBuffer::Format format) {
   switch (format) {
     case gfx::GpuMemoryBuffer::RGBA_8888:
     case gfx::GpuMemoryBuffer::RGBX_8888:
     case gfx::GpuMemoryBuffer::BGRA_8888:
-      return 4;
+      return 32;
   }
 
   NOTREACHED();
   return 0;
 }
 
+size_t 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;
+}
+
 class GpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
  public:
   GpuMemoryBufferImpl(const gfx::Size& size,
@@ -35,7 +41,7 @@ class GpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
   // Overridden from gfx::GpuMemoryBuffer:
   void* Map() override {
     DCHECK(!mapped_);
-    if (!shared_memory_->Map(size_.GetArea() * BytesPerPixel(format_)))
+    if (!shared_memory_->Map(PixelsToBytes(size_.GetArea(), format_)))
       return NULL;
     mapped_ = true;
     return shared_memory_->memory();
@@ -48,7 +54,7 @@ class GpuMemoryBufferImpl : public gfx::GpuMemoryBuffer {
   bool IsMapped() const override { return mapped_; }
   Format GetFormat() const override { return format_; }
   uint32 GetStride() const override {
-    return size_.width() * BytesPerPixel(format_);
+    return PixelsToBytes(size_.width(), format_);
   }
   gfx::GpuMemoryBufferHandle GetHandle() const override {
     gfx::GpuMemoryBufferHandle handle;
@@ -81,7 +87,7 @@ TestGpuMemoryBufferManager::AllocateGpuMemoryBuffer(
     gfx::GpuMemoryBuffer::Format format,
     gfx::GpuMemoryBuffer::Usage usage) {
   scoped_ptr<base::SharedMemory> shared_memory(new base::SharedMemory);
-  if (!shared_memory->CreateAnonymous(size.GetArea() * BytesPerPixel(format)))
+  if (!shared_memory->CreateAnonymous(PixelsToBytes(size.GetArea(), format)))
     return nullptr;
   return make_scoped_ptr<gfx::GpuMemoryBuffer>(
       new GpuMemoryBufferImpl(size, format, shared_memory.Pass()));