Add support for compressed GPU memory buffers.

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 196922f2fc94858242f124d8175eb9ea3dd965b6..7430051ea6ff16ad6d9160f8d6896b428be87d61 100644
--- a/cc/test/test_gpu_memory_buffer_manager.cc
+++ b/cc/test/test_gpu_memory_buffer_manager.cc
@@ -12,6 +12,14 @@ namespace {
 
 size_t StrideInBytes(size_t width, gfx::GpuMemoryBuffer::Format format) {
   switch (format) {
+    case gfx::GpuMemoryBuffer::ATCIA:
+    case gfx::GpuMemoryBuffer::DXT5:
+      return width;
+    case gfx::GpuMemoryBuffer::ATC:
+    case gfx::GpuMemoryBuffer::DXT1:
+    case gfx::GpuMemoryBuffer::ETC1:
+      DCHECK_EQ(width % 2, 0U);
+      return width / 2;
     case gfx::GpuMemoryBuffer::RGBA_8888:
     case gfx::GpuMemoryBuffer::RGBX_8888:
     case gfx::GpuMemoryBuffer::BGRA_8888: