gpu: Workaround Adreno 420 bug with deleting current FBO.

gpu/command_buffer/service/framebuffer_manager.h

Index: gpu/command_buffer/service/framebuffer_manager.h
diff --git a/gpu/command_buffer/service/framebuffer_manager.h b/gpu/command_buffer/service/framebuffer_manager.h
index 78c11ad2244cef39f87106fe82bceae84f56f7bf..c73678f75bc6739c386fb7f34d1f2f422033918a 100644
--- a/gpu/command_buffer/service/framebuffer_manager.h
+++ b/gpu/command_buffer/service/framebuffer_manager.h
@@ -74,6 +74,10 @@ class GPU_EXPORT Framebuffer : public base::RefCounted<Framebuffer> {
     GLenum attachment,
     bool cleared);
 
+  // Unbinds all attachments from this framebuffer.  The framebuffer must be
+  // bound when calling this.
+  void UnbindAttachments(GLenum target);

[no sievers, 2015/02/17 22:49:54]

Can you rename it to something so that it doesn't accidentally get used in the
wrong way, and since it leaves the object in an inconsistent state (compared
with UnbindRenderbuffer/Texture for example)?

DoUnbindGLAttachmentsForWorkaround() or something :)

[vmiura, 2015/02/18 17:43:18]

Done.

+
   // Attaches a renderbuffer to a particlar attachment.
   // Pass null to detach.
   void AttachRenderbuffer(