From b060891f8991060041a6fe5b632d10b06afe520d Mon Sep 17 00:00:00 2001
From: Seth Fowler <mark.seth.fowler@gmail.com>
Date: Sat, 19 Sep 2015 16:21:02 -0700
Subject: [PATCH] Bug 1146663 (Part 3) - Make it impossible to deoptimize
 imgFrames. r=tn

---
 image/imgFrame.cpp | 84 ++--------------------------------------------
 image/imgFrame.h   |  4 ++-
 2 files changed, 5 insertions(+), 83 deletions(-)

diff --git a/image/imgFrame.cpp b/image/imgFrame.cpp
index f48794d1d76c..803c63f60b43 100644
--- a/image/imgFrame.cpp
+++ b/image/imgFrame.cpp
@@ -796,88 +796,8 @@ imgFrame::LockImageData()
     return NS_OK;
   }
 
-  return Deoptimize();
-}
-
-nsresult
-imgFrame::Deoptimize()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  mMonitor.AssertCurrentThreadOwns();
-  MOZ_ASSERT(!mImageSurface);
-
-  if (!mImageSurface) {
-    if (mVBuf) {
-      VolatileBufferPtr<uint8_t> ref(mVBuf);
-      if (ref.WasBufferPurged()) {
-        return NS_ERROR_FAILURE;
-      }
-
-      mImageSurface = CreateLockedSurface(mVBuf, mSize, mFormat);
-      if (!mImageSurface) {
-        return NS_ERROR_OUT_OF_MEMORY;
-      }
-    }
-    if (mOptSurface || mSinglePixel || mFormat == SurfaceFormat::R5G6B5) {
-      SurfaceFormat format = mFormat;
-      if (mFormat == SurfaceFormat::R5G6B5) {
-        format = SurfaceFormat::B8G8R8A8;
-      }
-
-      // Recover the pixels
-      RefPtr<VolatileBuffer> buf =
-        AllocateBufferForImage(mSize, format);
-      if (!buf) {
-        return NS_ERROR_OUT_OF_MEMORY;
-      }
-
-      RefPtr<DataSourceSurface> surf =
-        CreateLockedSurface(buf, mSize, format);
-      if (!surf) {
-        return NS_ERROR_OUT_OF_MEMORY;
-      }
-
-      DataSourceSurface::MappedSurface mapping;
-      if (!surf->Map(DataSourceSurface::MapType::WRITE, &mapping)) {
-        gfxCriticalError() << "imgFrame::Deoptimize failed to map surface";
-        return NS_ERROR_FAILURE;
-      }
-
-      RefPtr<DrawTarget> target =
-        Factory::CreateDrawTargetForData(BackendType::CAIRO,
-                                         mapping.mData,
-                                         mSize,
-                                         mapping.mStride,
-                                         format);
-      if (!target) {
-        gfxWarning() <<
-          "imgFrame::Deoptimize failed in CreateDrawTargetForData";
-        return NS_ERROR_OUT_OF_MEMORY;
-      }
-
-      Rect rect(0, 0, mSize.width, mSize.height);
-      if (mSinglePixel) {
-        target->FillRect(rect, ColorPattern(mSinglePixelColor),
-                         DrawOptions(1.0f, CompositionOp::OP_SOURCE));
-      } else if (mFormat == SurfaceFormat::R5G6B5) {
-        target->DrawSurface(mImageSurface, rect, rect);
-      } else {
-        target->DrawSurface(mOptSurface, rect, rect,
-                            DrawSurfaceOptions(),
-                            DrawOptions(1.0f, CompositionOp::OP_SOURCE));
-      }
-      target->Flush();
-      surf->Unmap();
-
-      mFormat = format;
-      mVBuf = buf;
-      mImageSurface = surf;
-      mOptSurface = nullptr;
-    }
-  }
-
-  mVBufPtr = mVBuf;
-  return NS_OK;
+  MOZ_ASSERT_UNREACHABLE("It's illegal to re-lock an optimized imgFrame");
+  return NS_ERROR_FAILURE;
 }
 
 void
diff --git a/image/imgFrame.h b/image/imgFrame.h
index 89724c46f4ff..e5f62d01aa99 100644
--- a/image/imgFrame.h
+++ b/image/imgFrame.h
@@ -274,7 +274,6 @@ private: // methods
   nsresult LockImageData();
   nsresult UnlockImageData();
   nsresult Optimize();
-  nsresult Deoptimize();
 
   void AssertImageDataLocked() const;
 
@@ -448,6 +447,9 @@ private:
  * This may be considerably more expensive than is necessary just for drawing,
  * so only use this when you need to read or write the raw underlying image data
  * that the imgFrame holds.
+ *
+ * Once all an imgFrame's RawAccessFrameRefs go out of scope, new
+ * RawAccessFrameRefs cannot be created.
  */
 class RawAccessFrameRef final
 {