Add assertions that the empty Platform::cryptographicallyRandomValues() overrides are not being use…

third_party/WebKit/Source/web/ImageDecodeBench.cpp

 // 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.
 
 #ifdef WTF
 
 Provides a minimal wrapping of the Blink image decoders. Used to perform
 a non-threaded, memory-to-memory image decode using micro second accuracy
 clocks to measure image decode time. Optionally applies color correction
 during image decoding on supported platforms (default off). Usage:
@@ skipping 349 matching lines @@
 
     // Create a web platform without V8.
 
     class WebPlatform : public blink::Platform {
     public:
         const unsigned char* getTraceCategoryEnabledFlag(const char*) override
         {
             return reinterpret_cast<const unsigned char *>("nope-none-nada");
         }
 
         void cryptographicallyRandomValues(unsigned char*, size_t) override

[jww, 2015/11/10 18:43:16]

There was a comment in one of the other classes explaining that this needs to be
overridden to be useful/secure; maybe copy that comment here, too? Or at least
have a comment explaining the security concern.

[eroman, 2015/11/10 19:26:14]

The existing comment here was wrong here which is why I deleted it (there is no
"default" that gets used if this function does nothing).

I could add a comment explaining that this needs to be implemented if it is
used?

         {
-            // Do nothing: make blink::Platform use the default crypto-randoms.
+            ASSERT_NOT_REACHED();
         }
 
         void screenColorProfile(WebVector<char>* profile) override
         {
             getScreenColorProfile(profile); // Returns a whacked color profile.
         }
     };
 
     blink::initializeWithoutV8(new WebPlatform());
 
@@ skipping 28 matching lines @@
             exit(3);
         }
     }
 
     // Results to stdout.
 
     double averageTime = totalTime / static_cast<double>(iterations);
     printf("%f %f\n", totalTime, averageTime);
     return 0;
 }