From 6f304e526d96f2459bbffa313acab03ad1b7f816 Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Wed, 9 Apr 2014 21:15:18 +1200
Subject: [PATCH] Bug 991513 - Part 1: Don't lock ContentClientDoubleBuffered's
 texture until we need the buffers. r=nrc

---
 gfx/layers/RotatedBuffer.cpp        |  6 +++---
 gfx/layers/client/ContentClient.cpp | 22 +++++++++++-----------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/gfx/layers/RotatedBuffer.cpp b/gfx/layers/RotatedBuffer.cpp
index cdd195bf6aa..f9ff0be335e 100644
--- a/gfx/layers/RotatedBuffer.cpp
+++ b/gfx/layers/RotatedBuffer.cpp
@@ -499,14 +499,14 @@ RotatedContentBuffer::BeginPaint(ThebesLayer* aLayer,
 
   result.mRegionToDraw.Sub(neededRegion, validRegion);
 
+  if (result.mRegionToDraw.IsEmpty())
+    return result;
+
   // Do not modify result.mRegionToDraw or result.mContentType after this call.
   // Do not modify mBufferRect, mBufferRotation, or mDidSelfCopy,
   // or call CreateBuffer before this call.
   FinalizeFrame(result.mRegionToDraw);
 
-  if (result.mRegionToDraw.IsEmpty())
-    return result;
-
   nsIntRect drawBounds = result.mRegionToDraw.GetBounds();
   RefPtr<DrawTarget> destDTBuffer;
   RefPtr<DrawTarget> destDTBufferOnWhite;
diff --git a/gfx/layers/client/ContentClient.cpp b/gfx/layers/client/ContentClient.cpp
index 3149c3a63ee..e424339714b 100644
--- a/gfx/layers/client/ContentClient.cpp
+++ b/gfx/layers/client/ContentClient.cpp
@@ -156,10 +156,10 @@ ContentClientRemoteBuffer::EndPaint()
   }
   mOldTextures.Clear();
 
-  if (mTextureClient) {
+  if (mTextureClient && mTextureClient->IsLocked()) {
     mTextureClient->Unlock();
   }
-  if (mTextureClientOnWhite) {
+  if (mTextureClientOnWhite && mTextureClientOnWhite->IsLocked()) {
     mTextureClientOnWhite->Unlock();
   }
 }
@@ -382,15 +382,6 @@ ContentClientDoubleBuffered::PrepareFrame()
 {
   mIsNewBuffer = false;
 
-  if (mTextureClient) {
-    DebugOnly<bool> locked = mTextureClient->Lock(OPEN_READ_WRITE);
-    MOZ_ASSERT(locked);
-  }
-  if (mTextureClientOnWhite) {
-    DebugOnly<bool> locked = mTextureClientOnWhite->Lock(OPEN_READ_WRITE);
-    MOZ_ASSERT(locked);
-  }
-
   if (!mFrontAndBackBufferDiffer) {
     return;
   }
@@ -415,6 +406,15 @@ ContentClientDoubleBuffered::PrepareFrame()
 void
 ContentClientDoubleBuffered::FinalizeFrame(const nsIntRegion& aRegionToDraw)
 {
+  if (mTextureClient) {
+    DebugOnly<bool> locked = mTextureClient->Lock(OPEN_READ_WRITE);
+    MOZ_ASSERT(locked);
+  }
+  if (mTextureClientOnWhite) {
+    DebugOnly<bool> locked = mTextureClientOnWhite->Lock(OPEN_READ_WRITE);
+    MOZ_ASSERT(locked);
+  }
+
   if (!mFrontAndBackBufferDiffer) {
     MOZ_ASSERT(!mDidSelfCopy, "If we have to copy the world, then our buffers are different, right?");
     return;