Avoid overflow when checking if a transform is integer translation.

ui/gfx/transform.h

Index: ui/gfx/transform.h
diff --git a/ui/gfx/transform.h b/ui/gfx/transform.h
index 469f6e03c38c695f86cea1fa284300e82687f296..a942bd6c2a2f8d53add0927c26fb0b6445aa22bf 100644
--- a/ui/gfx/transform.h
+++ b/ui/gfx/transform.h
@@ -140,8 +140,10 @@ class GFX_EXPORT Transform {
            matrix_.get(2, 2) > 0.0;
   }
 
-  // Returns true if the matrix is either identity or pure, non-fractional
-  // translation.
+  // Returns true if the matrix is identity or, if the matrix consists only
+  // of a translation whose components can be represented as integers. Returns
+  // false if the translation contains a fractional component or is too large to
+  // fit in an integer.
   bool IsIdentityOrIntegerTranslation() const;
 
   // Returns true if the matrix had only scaling components.