<third_party/WebKit> [Backport] Lock the bitmap before calling getPixels().

On calling getPixels() after decoding always return NULL as
SkBitmap fpixels is set to NULL while copying.

BUG=490549
TEST=Existing

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=195570

Task-number: QTBUG-48822
Change-Id: I7cb9add182524cb9a9093416b96d7e1843df7b70
Reviewed-by: Kai Koehne <[email protected]>

Author: Michael Brüning

chromium/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp

@@ -142,6 +142,7 @@ bool ImageFrameGenerator::decodeAndScale(const SkImageInfo& info, size_t index,
     ASSERT(bitmap.height() == scaledSize.height());
 
     bool result = true;
+    SkAutoLockPixels bitmapLock(bitmap);
     // Check to see if decoder has written directly to the memory provided
     // by Skia. If not make a copy.
     if (bitmap.getPixels() != pixels)