Bevacizumab in Combination With Vinorelbine and Trastuzumab for HER2-Positive, Metastatic Breast Cancer

* Participants will receive bevacizumab intravenously every 2 weeks. They will also receive trastuzumab and vinorelbine intravenously once a week. Therefore, treatments will alternate between receiving all three drugs (1st week, third week, fifth week, etc.) and receiving only trastuzumab and vinorelbine (2nd week, fourth week, sixth week, etc.) A treatment cycle lasts four weeks. * During all treatment cycles a physical exam will be performed and the participant will be asked general health and specific questions about any problems they are experiencing. * X-ray, CT scans, and/or MRI scans will be performed every 8 weeks (every 2 cycles) in order to assess the effect of the study treatment on the participants cancer. These tests are considered standard of care in patients receiving chemotherapy. * Once a week blood counts will be performed and at least every 4 weeks, chemistry and other tests to measure any additional effect of the study drug and disease status will be checked. These tests are also considered standard of care for patients receiving chemotherapy. * At the beginning of the study and at the 4- and 8-week time point, additional blood will be drawn in order to conduct research blood tests to measure the presence of cancer cells in the blood. * A urine test and MUGA scan or echocardiogram will be done every 8 weeks while the participant in on the study. * Participants can remain on the research study as long as the study treatment appears to be working and they are not experiencing unacceptable side effects.