Add Intel DRM backed GpuMemoryBuffer implementation.

content/common/gpu/client/gpu_channel_host.cc

Index: content/common/gpu/client/gpu_channel_host.cc
diff --git a/content/common/gpu/client/gpu_channel_host.cc b/content/common/gpu/client/gpu_channel_host.cc
index afc0b5993c7e548060235b95bf1b865bf92bbe66..eefde9833e53b14bbe58050adf895dfb5e17be07 100644
--- a/content/common/gpu/client/gpu_channel_host.cc
+++ b/content/common/gpu/client/gpu_channel_host.cc
@@ -47,6 +47,9 @@ bool GpuChannelHost::IsValidGpuMemoryBuffer(
     gfx::GpuMemoryBufferHandle handle) {
   switch (handle.type) {
     case gfx::SHARED_MEMORY_BUFFER:
+#if defined(OS_LINUX)
+    case gfx::INTEL_DRM_BUFFER:
+#endif
 #if defined(OS_MACOSX)
     case gfx::IO_SURFACE_BUFFER:
 #endif
@@ -277,9 +280,12 @@ int32 GpuChannelHost::ReserveTransferBufferId() {
 gfx::GpuMemoryBufferHandle GpuChannelHost::ShareGpuMemoryBufferToGpuProcess(
     gfx::GpuMemoryBufferHandle source_handle) {
   switch (source_handle.type) {
+#if defined(OS_LINUX)
+    case gfx::INTEL_DRM_BUFFER:
+#endif
     case gfx::SHARED_MEMORY_BUFFER: {
       gfx::GpuMemoryBufferHandle handle;
-      handle.type = gfx::SHARED_MEMORY_BUFFER;
+      handle.type = source_handle.type;
       handle.handle = ShareToGpuProcess(source_handle.handle);
       return handle;
     }