Initialize the bitmap before drawing the VideoFrame into it, in case

content/browser/renderer_host/render_widget_host_view_browsertest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "content/browser/gpu/compositor_util.h"
 #include "content/browser/gpu/gpu_data_manager_impl.h"
@@ skipping 474 matching lines @@
       return;
     }
 
     media::SkCanvasVideoRenderer video_renderer;
 
     SkBitmap bitmap;
     bitmap.allocPixels(SkImageInfo::Make(video_frame->visible_rect().width(),
                                          video_frame->visible_rect().height(),
                                          kPMColor_SkColorType,
                                          kPremul_SkAlphaType));
-    bitmap.allocPixels();
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
     SkCanvas canvas(bitmap);
 
     video_renderer.Paint(video_frame.get(),
                          &canvas,
                          video_frame->visible_rect(),
                          0xff);
 
     CopyFromCompositingSurfaceCallback(quit_callback,
                                        result,
                                        bitmap);
@@ skipping 351 matching lines @@
                         CompositingRenderWidgetHostViewBrowserTestTabCapture,
                         testing::ValuesIn(kAllCompositingModes));
 INSTANTIATE_TEST_CASE_P(GLAndSoftwareCompositing,
                         CompositingRenderWidgetHostViewTabCaptureHighDPI,
                         testing::ValuesIn(kAllCompositingModes));
 
 #endif  // !defined(OS_ANDROID) && !defined(OS_IOS)
 
 }  // namespace
 }  // namespace content