Revert of wtf/CheckedArithmetic.h delegates to base/numerics/safe_math.h.

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index 0f476e9bdf5432704f9c742a60f2edd27dc87b9e..80d196bcc1ba02d4519451fad4f66b009db6d91f 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -67,7 +67,6 @@
 #include "platform/transforms/AffineTransform.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebTraceLocation.h"
-#include "wtf/CheckedNumeric.h"
 #include <math.h>
 #include <v8.h>
 
@@ -828,13 +827,15 @@
         bufferCount++;
 
     // Four bytes per pixel per buffer.
-    CheckedNumeric<intptr_t> checkedExternallyAllocatedMemory = 4 * bufferCount;
+    Checked<intptr_t, RecordOverflow> checkedExternallyAllocatedMemory = 4 * bufferCount;
     if (is3D())
         checkedExternallyAllocatedMemory += m_context->externallyAllocatedBytesPerPixel();
 
     checkedExternallyAllocatedMemory *= width();
     checkedExternallyAllocatedMemory *= height();
-    intptr_t externallyAllocatedMemory = checkedExternallyAllocatedMemory.ValueOrDefault(std::numeric_limits<intptr_t>::max());
+    intptr_t externallyAllocatedMemory;
+    if (checkedExternallyAllocatedMemory.safeGet(externallyAllocatedMemory) == CheckedState::DidOverflow)
+        externallyAllocatedMemory = std::numeric_limits<intptr_t>::max();
 
     // Subtracting two intptr_t that are known to be positive will never underflow.
     v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(externallyAllocatedMemory - m_externallyAllocatedMemory);