Oilpan: Remove "this" argument of registerPreFinalizer() from documentation.

BUG=544756
R=haraken@chromium.org, oilpan-reviews@chromium.org, sigbjornf@opera.com

Review URL: https://codereview.chromium.org/1471193003

Cr-Commit-Position: refs/heads/master@{#361301}

third_party/WebKit/Source/platform/heap/BlinkGCAPIReference.md

@@ -99,7 +99,7 @@ with a destructor.
 A pre-finalizer must have the following function signature: `void preFinalizer()`. You can change the function name.
 
 A pre-finalizer must be registered in the constructor by using the following statement:
-"`ThreadState::current()->registerPreFinalizer(this, preFinalizerName);`".
+"`ThreadState::current()->registerPreFinalizer(preFinalizerName);`".
 
 ```c++
 class YourClass : public GarbageCollectedFinalized<YourClass> {
@@ -107,7 +107,7 @@ class YourClass : public GarbageCollectedFinalized<YourClass> {
 public:
     YourClass()
     {
-        ThreadState::current()->registerPreFinalizer(this, dispose);
+        ThreadState::current()->registerPreFinalizer(dispose);
     }
     void dispose()
     {

third_party/WebKit/Source/platform/heap/ThreadState.h

@@ -92,7 +92,7 @@ class Visitor;
 // public:
 //     Foo()
 //     {
-//         ThreadState::current()->registerPreFinalizer(this, dispose);
+//         ThreadState::current()->registerPreFinalizer(dispose);
 //     }
 // private:
 //     void dispose()