A Study to Investigate the Efficacy and Safety of Bendamustine Compared With Bendamustine+Obinutuzumab (GA101) in Participants With Rituximab-Refractory, Indolent Non-Hodgkin's Lymphoma (GADOLIN)

Inclusion Criteria:

* History of histologically documented, B-lymphocyte antigen cluster of differentiation 20 plus (CD20+), iNHL
* Refractory to any previous regimen containing rituximab (defined by participants who did not respond or who progressed during or up to 6 months after treatment with rituximab or a rituximab-containing regimen)
* Previously treated with a maximum of four unique chemotherapy containing treatment regimens
* All participants must have at least one bi-dimensionally measurable lesion (greater than \[\>\]1.5 centimeters (cm) in its largest dimension by computed tomography \[CT\] scan)

Exclusion Criteria:

* Prior use of any monoclonal antibody (other than anti-CD20) within 3 months prior to the start of Cycle 1, prior treatment with obinutuzumab was not allowed
* Chemotherapy or other investigational therapy within 28 days prior to the start of Cycle 1
* Prior treatment with bendamustine (within 2 years of the start of Cycle 1)
* Prior allogeneic stem cell transplant
* History of severe allergic or anaphylactic reactions to monoclonal antibody therapy
* History of sensitivity to mannitol
* Central nervous system lymphoma or prior diffuse large B-cell lymphoma (DLBCL), histological evidence of transformation to high grade or diffuse large B-cell lymphoma
* History of other malignancy that could affect compliance with the protocol or interpretation of results
* Evidence of significant, uncontrolled concomitant diseases that could affect compliance with the protocol or interpretation of results
* Known active bacterial, viral, fungal, mycobacterial, parasitic, or other infection (excluding fungal infections of nail beds) or any major episode of infection requiring treatment with intravenous antibiotics or hospitalization within 4 weeks
* Participants with a history of confirmed progressive multifocal leukoencephalopathy (PML)
* Vaccination with a live vaccine a minimum of 28 days prior to randomization
* Recent major surgery (within 4 weeks), other than for diagnosis
* Presence of positive test results for Hepatitis B surface antigen (HBsAg); antibody to hepatitis B core antigen \[anti-HBc\]) with detectable viral load (positive hepatitis B virus \[HBV\] deoxyribo-nucleic acid \[DNA\]) or Hepatitis C
* Participants with chronic hepatitis B or seropositive occult (HBV) infection
* Participants with seronegative occult HBV infection or past HBV infection (defined as anti-HBc positive and HBV DNA negative) could be eligible if they were willing to be followed according to the protocol for HBV DNA testing
* Participants positive for Hepatitis C virus (HCV) antibody were eligible only if polymerase chain reaction(PCR) was negative for HCV Ribonucleic acid (RNA)
* Known history of human immunodeficiency virus (HIV) seropositive status
* Positive test results for human T-lymphotropic virus type I (HTLV 1) virus in endemic countries
* Women who are pregnant or lactating
* Fertile men or women of childbearing potential unless 1) surgically sterile or 2) using an adequate measure of contraception such as oral contraceptives, intrauterine device, or barrier method of contraception in conjunction with spermicidal jelly
* Ongoing corticosteroid use \>30 milligrams per day (mg/day) prednisone or equivalent