import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1159409 - (Part 1-) - Remove Init() from the Image interface. r=tn (0b663ee45)
- Bug 1159409 - (Part 2) - Remove ProgressTrackerInit and register Images with a ProgressTracker in ImageFactory. r=tn (a24d4e849)
- Bug 1179909: Refactor stable state handling. r=smaug This is motivated by three separate but related problems: (0ead73dbd)
- remove mPreemptingRunnableInfos of PM which I couldn't trace in FF (96474c90a)
- Bug 1179909: Build fix. r=me CLOSED TREE (5d35a65d5)
- Bug 1144418 - target events for text nodes in shadow dom to the nearest element in the flattened tree. r=wchen (26c0eb8b2)
- Bug 853889 - Check single-box orientaton in _cairo_bentley_ottmann_tessellate_rectangular_traps and _cairo_bentley_ottmann_tessellate_boxes. r=jmuizelaar (a13abee2f)
- Bug 1143303 - extend D2D circle workaround to work for small circles. r=bas (1ccb1c0c1)

xpcom/threads/nsThread.cpp

@@ -22,6 +22,7 @@
 #include "nsAutoPtr.h"
 #include "nsCOMPtr.h"
 #include "pratom.h"
+#include "mozilla/CycleCollectedJSRuntime.h"
 #include "mozilla/Logging.h"
 #include "nsIObserverService.h"
 #if !defined(MOZILLA_XPCOMRT_API)
@@ -89,8 +90,6 @@ GetThreadLog()
 
 NS_DECL_CI_INTERFACE_GETTER(nsThread)
 
-nsIThreadObserver* nsThread::sMainThreadObserver = nullptr;
-
 //-----------------------------------------------------------------------------
 // Because we do not have our own nsIFactory, we have to implement nsIClassInfo
 // somewhat manually.
@@ -407,6 +406,7 @@ int sCanaryOutputFD = -1;
 
 nsThread::nsThread(MainThreadFlag aMainThread, uint32_t aStackSize)
   : mLock("nsThread.mLock")
+  , mScriptObserver(nullptr)
   , mEvents(&mEventsRoot)
   , mPriority(PRIORITY_NORMAL)
   , mThread(nullptr)
@@ -791,22 +791,19 @@ nsThread::ProcessNextEvent(bool aMayWait, bool* aResult)
   }
 #endif
 
-  bool notifyMainThreadObserver =
-    (MAIN_THREAD == mIsMainThread) && sMainThreadObserver;
-  if (notifyMainThreadObserver) {
-    sMainThreadObserver->OnProcessNextEvent(this, reallyWait,
-                                            mNestedEventLoopDepth);
+  ++mNestedEventLoopDepth;
+
+  bool callScriptObserver = !!mScriptObserver;
+  if (callScriptObserver) {
+    mScriptObserver->BeforeProcessTask(reallyWait);
   }
 
   nsCOMPtr<nsIThreadObserver> obs = mObserver;
   if (obs) {
-    obs->OnProcessNextEvent(this, reallyWait, mNestedEventLoopDepth);
+    obs->OnProcessNextEvent(this, reallyWait);
   }
 
-  NOTIFY_EVENT_OBSERVERS(OnProcessNextEvent,
-                         (this, reallyWait, mNestedEventLoopDepth));
-
-  ++mNestedEventLoopDepth;
+  NOTIFY_EVENT_OBSERVERS(OnProcessNextEvent, (this, reallyWait));
 
 #ifdef MOZ_CANARY
   Canary canary;
@@ -839,20 +836,18 @@ nsThread::ProcessNextEvent(bool aMayWait, bool* aResult)
     }
   }
 
-  --mNestedEventLoopDepth;
-
-  NOTIFY_EVENT_OBSERVERS(AfterProcessNextEvent,
-                         (this, mNestedEventLoopDepth, *aResult));
+  NOTIFY_EVENT_OBSERVERS(AfterProcessNextEvent, (this, *aResult));
 
   if (obs) {
-    obs->AfterProcessNextEvent(this, mNestedEventLoopDepth, *aResult);
+    obs->AfterProcessNextEvent(this, *aResult);
   }
 
-  if (notifyMainThreadObserver && sMainThreadObserver) {
-    sMainThreadObserver->AfterProcessNextEvent(this, mNestedEventLoopDepth,
-                                               *aResult);
+  if (callScriptObserver && mScriptObserver) {
+    mScriptObserver->AfterProcessTask(mNestedEventLoopDepth);
   }
 
+  --mNestedEventLoopDepth;
+
   return rv;
 }
 
@@ -929,15 +924,11 @@ nsThread::SetObserver(nsIThreadObserver* aObs)
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsThread::GetRecursionDepth(uint32_t* aDepth)
+uint32_t
+nsThread::RecursionDepth() const
 {
-  if (NS_WARN_IF(PR_GetCurrentThread() != mThread)) {
-    return NS_ERROR_NOT_SAME_THREAD;
-  }
-
-  *aDepth = mNestedEventLoopDepth;
-  return NS_OK;
+  MOZ_ASSERT(PR_GetCurrentThread() == mThread);
+  return mNestedEventLoopDepth;
 }
 
 NS_IMETHODIMP
@@ -1036,19 +1027,16 @@ nsThread::PopEventQueue(nsIEventTarget* aInnermostTarget)
   return NS_OK;
 }
 
-nsresult
-nsThread::SetMainThreadObserver(nsIThreadObserver* aObserver)
+void
+nsThread::SetScriptObserver(mozilla::CycleCollectedJSRuntime* aScriptObserver)
 {
-  if (aObserver && nsThread::sMainThreadObserver) {
-    return NS_ERROR_NOT_AVAILABLE;
+  if (!aScriptObserver) {
+    mScriptObserver = nullptr;
+    return;
   }
 
-  if (!NS_IsMainThread()) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  nsThread::sMainThreadObserver = aObserver;
-  return NS_OK;
+  MOZ_ASSERT(!mScriptObserver);
+  mScriptObserver = aScriptObserver;
 }
 
 //-----------------------------------------------------------------------------