Bug 635464: Diagnostic crash in nightly and aurora, to see if we are asking basic content client for alpha. r=bas

MozReview-Commit-ID: 2DBdJZs0hlh

--HG--
extra : rebase_source : dabafda100d50b8308e4dc008254a7a4c6d80549

gfx/2d/Logging.h

@@ -126,6 +126,7 @@ enum class LogReason : int {
   AsyncTransactionTimeout, // 30
   TextureCreation,
   InvalidCacheSurface,
+  AlphaWithBasicClient,
   // End
   MustBeLessThanThis = 101,
 };

gfx/layers/client/ContentClient.cpp

@@ -127,6 +127,9 @@ ContentClientBasic::CreateBuffer(ContentType aType,
                                  RefPtr<gfx::DrawTarget>* aWhiteDT)
 {
   MOZ_ASSERT(!(aFlags & BUFFER_COMPONENT_ALPHA));
+  if (aFlags & BUFFER_COMPONENT_ALPHA) {
+    gfxDevCrash(LogReason::AlphaWithBasicClient) << "Asking basic content client for component alpha";
+  }
 
   *aBlackDT = gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
     IntSize(aRect.width, aRect.height),