cc: Use CheckedNumeric for resource size calculations.

cc/resources/resource_provider.cc

 // Copyright 2012 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/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/hash_tables.h"
 #include "base/metrics/histogram.h"
+#include "base/numerics/safe_math.h"
 #include "base/stl_util.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/resources/platform_color.h"
 #include "cc/resources/returned_resource.h"
 #include "cc/resources/shared_bitmap_manager.h"
 #include "cc/resources/texture_uploader.h"
 #include "cc/resources/transferable_resource.h"
@@ skipping 743 matching lines @@
   } else {
     DCHECK(resource->gl_id);
     DCHECK(!resource->pending_set_pixels);
     DCHECK_EQ(resource->target, static_cast<GLenum>(GL_TEXTURE_2D));
     GLES2Interface* gl = ContextGL();
     DCHECK(gl);
     DCHECK(texture_uploader_.get());
     gl->BindTexture(GL_TEXTURE_2D, resource->gl_id);
 
     if (resource->format == ETC1) {
-      // TODO(vmpstr): Make this overflow safe. crbug.com/495867
-      int num_bytes =
-          image_size.width() * image_size.height() * BitsPerPixel(ETC1) / 8;
+      base::CheckedNumeric<int> num_bytes = BitsPerPixel(ETC1);

[danakj, 2015/06/04 19:02:38]

This function is called with less trustworthy info, eg called with the size of a
video frame resource. I don't think we can guarantee anything there. So always
Checking here sounds right to me.

+      num_bytes *= image_size.width();
+      num_bytes *= image_size.height();
+      num_bytes /= 8;
       gl->CompressedTexImage2D(GL_TEXTURE_2D, 0, GLInternalFormat(ETC1),
                                image_size.width(), image_size.height(), 0,
-                               num_bytes, image);
+                               num_bytes.ValueOrDie(), image);
     } else {
       gl->TexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, image_size.width(),
                         image_size.height(), GLDataFormat(resource->format),
                         GLDataType(resource->format), image);
     }
   }
 }
 
 size_t ResourceProvider::NumBlockingUploads() {
   if (!texture_uploader_)
@@ skipping 1265 matching lines @@
 }
 
 class GrContext* ResourceProvider::GrContext(bool worker_context) const {
   ContextProvider* context_provider =
       worker_context ? output_surface_->worker_context_provider()
                      : output_surface_->context_provider();
   return context_provider ? context_provider->GrContext() : NULL;
 }
 
 }  // namespace cc