Add R_8 GPU memory buffers format.

gpu/command_buffer/service/image_factory.cc

Index: gpu/command_buffer/service/image_factory.cc
diff --git a/gpu/command_buffer/service/image_factory.cc b/gpu/command_buffer/service/image_factory.cc
index a80d17c8ddbff0dd25c3bd1dead32e54c8963942..e81522b3f938a17942fe6923ae7908ca8cee6fa4 100644
--- a/gpu/command_buffer/service/image_factory.cc
+++ b/gpu/command_buffer/service/image_factory.cc
@@ -19,6 +19,8 @@ ImageFactory::~ImageFactory() {
 gfx::GpuMemoryBuffer::Format ImageFactory::ImageFormatToGpuMemoryBufferFormat(
     unsigned internalformat) {
   switch (internalformat) {
+    case GL_R8:
+      return gfx::GpuMemoryBuffer::R_8;
     case GL_RGB:
       return gfx::GpuMemoryBuffer::RGBX_8888;
     case GL_RGBA:
@@ -78,6 +80,8 @@ bool ImageFactory::IsGpuMemoryBufferFormatSupported(
       return capabilities.texture_format_dxt5;
     case gfx::GpuMemoryBuffer::ETC1:
       return capabilities.texture_format_etc1;
+    case gfx::GpuMemoryBuffer::R_8:
+      return capabilities.texture_rg;
     case gfx::GpuMemoryBuffer::RGBA_8888:
     case gfx::GpuMemoryBuffer::RGBX_8888:
       return true;
@@ -100,6 +104,7 @@ bool ImageFactory::IsImageSizeValidForGpuMemoryBufferFormat(
       // Compressed images must have a width and height that's evenly divisible
       // by the block size.
       return size.width() % 4 == 0 && size.height() % 4 == 0;
+    case gfx::GpuMemoryBuffer::R_8:
     case gfx::GpuMemoryBuffer::RGBA_8888:
     case gfx::GpuMemoryBuffer::BGRA_8888:
     case gfx::GpuMemoryBuffer::RGBX_8888: