Fix end-of-pattern matching for Skia recording optimization.

The recorder optimizer's pattern matcher was accepting command sequences
when it shouldn't have.

In the submitted case, and the pattern matcher was looking for:
	saveLayer, drawBitmap, restore
and in the rendering for the submitted case, the sequence of commands
were:
	saveLayer, drawBitmap, drawBitmap, restore

This sequence was improperly accepted by the matcher, and the optimizer
reduced the sequence to:
	drawBitmap, drawBitmap
where the opacity from the saveLayer paint argument was applied
to the first drawBitmap only.

The user-visible effect in Chrome was a flashing effect on an image
caused by incorrect (too-high) opacity.

The patch adds a Skia test to check for pixel colour values in
a similarly structured recording.  All other Skia tests pass.
Blink layout tests also pass with this change.

BUG=chromium:344987
R=robertphillips@google.com, reed@google.com, mtklein@google.com

Author: dneto@chromium.org

Review URL: https://codereview.chromium.org/430503004

1 files changed, 0 insertions, 1 deletions

diff --git a/src/core/SkPictureRecord.cpp b/src/core/SkPictureRecord.cpp
index 566cb196ba..ab4c3fa38e 100644
--- a/src/core/SkPictureRecord.cpp
+++ b/src/core/SkPictureRecord.cpp
@@ -319,7 +319,6 @@ static bool match(SkWriter32* writer, uint32_t offset,
         return false;
     }
 
-    curOffset += curSize;
     if (curOffset < writer->bytesWritten()) {
         // Something else between the last command and the end of the stream
         return false;