Revert of Remove DCHECK_IMPLIES/CHECK_IMPLIES.

content/common/discardable_shared_memory_heap.cc

 // Copyright 2014 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 "content/common/discardable_shared_memory_heap.h"
 
 #include <algorithm>
 
 #include "base/format_macros.h"
 #include "base/memory/discardable_shared_memory.h"
@@ skipping 158 matching lines @@
   InsertIntoFreeList(span.Pass());
 }
 
 scoped_ptr<DiscardableSharedMemoryHeap::Span>
 DiscardableSharedMemoryHeap::Split(Span* span, size_t blocks) {
   DCHECK(blocks);
   DCHECK_LT(blocks, span->length_);
 
   scoped_ptr<Span> leftover(new Span(
       span->shared_memory_, span->start_ + blocks, span->length_ - blocks));
-  DCHECK(leftover->length_ == 1 ||
-         spans_.find(leftover->start_) == spans_.end());
+  DCHECK_IMPLIES(leftover->length_ > 1,
+                 spans_.find(leftover->start_) == spans_.end());
   RegisterSpan(leftover.get());
   spans_[span->start_ + blocks - 1] = span;
   span->length_ = blocks;
   return leftover.Pass();
 }
 
 scoped_ptr<DiscardableSharedMemoryHeap::Span>
 DiscardableSharedMemoryHeap::SearchFreeLists(size_t blocks, size_t slack) {
   DCHECK(blocks);
 
@@ skipping 83 matching lines @@
 
 scoped_ptr<DiscardableSharedMemoryHeap::Span>
 DiscardableSharedMemoryHeap::Carve(Span* span, size_t blocks) {
   scoped_ptr<Span> serving = RemoveFromFreeList(span);
 
   const int extra = serving->length_ - blocks;
   if (extra) {
     scoped_ptr<Span> leftover(
         new Span(serving->shared_memory_, serving->start_ + blocks, extra));
     leftover->set_is_locked(false);
-    DCHECK(extra == 1 || spans_.find(leftover->start_) == spans_.end());
+    DCHECK_IMPLIES(extra > 1, spans_.find(leftover->start_) == spans_.end());
     RegisterSpan(leftover.get());
 
     // No need to coalesce as the previous span of |leftover| was just split
     // and the next span of |leftover| was not previously coalesced with
     // |span|.
     InsertIntoFreeList(leftover.Pass());
 
     serving->length_ = blocks;
     spans_[serving->start_ + blocks - 1] = serving.get();
   }
@@ skipping 154 matching lines @@
   ScopedVector<ScopedMemorySegment>::const_iterator it =
       std::find_if(memory_segments_.begin(), memory_segments_.end(),
                    [span](const ScopedMemorySegment* segment) {
                      return segment->ContainsSpan(span);
                    });
   DCHECK(it != memory_segments_.end());
   return (*it)->CreateMemoryAllocatorDump(span, block_size_, name, pmd);
 }
 
 }  // namespace content