Initialize our quads to zero before we gl_->BufferData() with them.

cc/output/dynamic_geometry_binding.cc

 // Copyright 2015 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 "cc/output/dynamic_geometry_binding.h"
 
 #include "cc/output/gl_renderer.h"  // For the GLC() macro.
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "ui/gfx/geometry/rect_f.h"
 
 namespace cc {
 
 DynamicGeometryBinding::DynamicGeometryBinding(gpu::gles2::GLES2Interface* gl)
     : gl_(gl), quad_vertices_vbo_(0), quad_elements_vbo_(0) {
-  GeometryBindingQuad quads[8];
-  GeometryBindingQuadIndex quad_indices[8];
+  GeometryBindingQuad quads[1];

[enne (OOO), 2015/02/27 21:36:01]

Can you initialize this in the class itself rather than here? If somebody else
ever instantiates it, they'll probably forget as well.

[awoloszyn, 2015/02/27 22:08:37]

Done.

+  GeometryBindingQuadIndex quad_indices[1];
 
   static_assert(sizeof(GeometryBindingQuad) == 24 * sizeof(float),
                 "struct Quad should be densely packed");
   static_assert(sizeof(GeometryBindingQuadIndex) == 6 * sizeof(uint16_t),
                 "struct QuadIndex should be densely packed");
 
+  memset(quads, 0x00, sizeof(quads));
+  memset(quads, 0x00, sizeof(quad_indices));
+
   GLC(gl_, gl_->GenBuffers(1, &quad_vertices_vbo_));
   GLC(gl_, gl_->GenBuffers(1, &quad_elements_vbo_));
 
   GLC(gl_, gl_->BindBuffer(GL_ARRAY_BUFFER, quad_vertices_vbo_));
   GLC(gl_, gl_->BufferData(GL_ARRAY_BUFFER, sizeof(GeometryBindingQuad) * 1,
                            quads, GL_DYNAMIC_DRAW));
 
   GLC(gl_, gl_->BindBuffer(GL_ELEMENT_ARRAY_BUFFER, quad_elements_vbo_));
   GLC(gl_, gl_->BufferData(GL_ELEMENT_ARRAY_BUFFER,
                            sizeof(GeometryBindingQuadIndex) * 1, &quad_indices,
@@ skipping 28 matching lines @@
                               &local_quad));
   GLC(gl_, gl_->BufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0,
                               sizeof(GeometryBindingQuadIndex), &quad_index));
 }
 
 void DynamicGeometryBinding::PrepareForDraw() {
   SetupGLContext(gl_, quad_elements_vbo_, quad_vertices_vbo_);
 }
 
 }  // namespace cc