Use mapped memory for uploading large textures.

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index e85929912f6af462e57c7e0ddbda2ee017f606fc..27779c958d51d34812da718c167e81bf3a24dcb6 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -2203,6 +2203,22 @@ void GLES2Implementation::TexImage2D(
     return;
   }
 
+  // Check if we can allocate shared memory to send it.
+  int32 mapped_shm_id = 0;
+  unsigned int mapped_shm_offset = 0;
+  void* mem = mapped_memory_->Alloc(size, &mapped_shm_id, &mapped_shm_offset);
+  if (mem) {
+    CopyRectToBuffer(
+        pixels, height, unpadded_row_size, src_padded_row_size, unpack_flip_y_,
+        mem, padded_row_size);
+    helper_->TexImage2D(
+        target, level, internalformat, width, height, format, type,
+        mapped_shm_id, mapped_shm_offset);
+    CheckGLError();
+    mapped_memory_->FreePendingToken(mem, helper_->InsertToken());

[piman, 2015/06/08 21:12:35]

Can you force a shallow flush here? Without it, the risk is that if the context
is never flushed (e.g. offscreen rasterization), we'll grow the mapped memory
unbounded (and then run out of address space or memory or file descriptors).

If we get here, that means we have to upload a large texture and the relative
cost of the flush will be minimal.

[David Yen, 2015/06/08 21:34:06]

Done. Although in order to do this in my new version I had to set a flag to do
the flush after releases in the scoped mapped memory class.

+    return;
+  }
+
   // No, so send it using TexSubImage2D.
   helper_->TexImage2D(
      target, level, internalformat, width, height, format, type,