Oilpan: rename GCState and GCReason values to reflect function only.

Source/core/frame/ImageBitmapTest.cpp

Index: Source/core/frame/ImageBitmapTest.cpp
diff --git a/Source/core/frame/ImageBitmapTest.cpp b/Source/core/frame/ImageBitmapTest.cpp
index 27648fb49d1d4e24aa9ba267ccbc72842b205363..a68d37b15b5fd2c7abbcd7635e020d46dd4a829f 100644
--- a/Source/core/frame/ImageBitmapTest.cpp
+++ b/Source/core/frame/ImageBitmapTest.cpp
@@ -70,7 +70,7 @@ protected:
         // Garbage collection is required prior to switching out the
         // test's memory cache; image resources are released, evicting
         // them from the cache.
-        Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGCForTesting);
+        Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
 
         replaceMemoryCacheForTesting(m_globalMemoryCache.release());
     }
@@ -156,7 +156,7 @@ TEST_F(ImageBitmapTest, ImageBitmapLiveResourcePriority)
         ASSERT_EQ(memoryCache()->priority(imageOutsideCrop->cachedImage()), MemoryCacheLiveResourcePriorityLow);
     }
     // Force a garbage collection to sweep out the local ImageBitmaps.
-    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGCForTesting);
+    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
 
     // CacheLiveResourcePriroity should return to CacheLiveResourcePriorityLow when no ImageBitmaps reference the image.
     ASSERT_EQ(memoryCache()->priority(imageNoCrop->cachedImage()), MemoryCacheLiveResourcePriorityLow);