Fix DeferredTextureImage test on Mac

Change-Id: I34cf12b2aa16b2441b9e57162cbaee1444f42c52
Reviewed-on: https://skia-review.googlesource.com/29607
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/tests/ImageTest.cpp b/tests/ImageTest.cpp
index 814dc9b..4ee2803 100644
--- a/tests/ImageTest.cpp
+++ b/tests/ImageTest.cpp
@@ -486,6 +486,9 @@
                 ERRORF(reporter, "makeTextureImage changed image alpha type.");
             }
         }
+
+        testContext->makeCurrent();
+        context->flush();
     }
 }
 
@@ -1123,6 +1126,9 @@
             }
             sk_free(buffer);
         }
+
+        testContext->makeCurrent();
+        context->flush();
     }
 }
 #endif
diff --git a/tests/ProxyTest.cpp b/tests/ProxyTest.cpp
index 547d3b2..a9b4643 100644
--- a/tests/ProxyTest.cpp
+++ b/tests/ProxyTest.cpp
@@ -251,6 +251,9 @@
                     if (renderable) {
                         desc.fFlags = kRenderTarget_GrSurfaceFlag;
                         tex = provider->createTexture(desc, budgeted);
+                        if (!tex) {
+                            continue; // This can fail on Mesa
+                        }
                         sk_sp<GrRenderTarget> rt(sk_ref_sp(tex->asRenderTarget()));
 
                         sk_sp<GrSurfaceProxy> sProxy(GrSurfaceProxy::MakeWrapped(rt, origin));