Bug 1197976 - Use runnable events for nsAppShell event loop; r=snorp

nsAppShell is currently based on AndroidGeckoEvent objects, which mirror
GeckoEvent on the Java side. With GeckoEvent going away, we will be
gradually removing AndroidGeckoEvent as well. This patch makes the
nsAppShell event loop based on runnable objects, which derive from
nsAppShell::Event. Using runnable objects is much more flexible and allows
us, for example, to post a lambda to the event loop to be run later.

widget/android/nsAppShell.cpp

@@ -30,9 +30,7 @@
 #include "nsCDefaultURIFixup.h"
 #include "nsToolkitCompsCID.h"
 
-#include "mozilla/HangMonitor.h"
 #include "mozilla/Services.h"
-#include "mozilla/unused.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Hal.h"
 #include "prenv.h"
@@ -185,10 +183,7 @@ public:
 };
 
 nsAppShell::nsAppShell()
-    : mQueueLock("nsAppShell.mQueueLock"),
-      mCondLock("nsAppShell.mCondLock"),
-      mQueueCond(mCondLock, "nsAppShell.mQueueCond"),
-      mQueuedViewportEvent(nullptr)
+    : mQueuedViewportEvent(nullptr)
 {
     gAppShell = this;
 
@@ -216,6 +211,10 @@ nsAppShell::nsAppShell()
 
 nsAppShell::~nsAppShell()
 {
+    while (mEventQueue.Pop(/* mayWait */ false)) {
+        NS_WARNING("Discarded event on shutdown");
+    }
+
     gAppShell = nullptr;
 
     if (sPowerManagerService) {
@@ -233,8 +232,7 @@ nsAppShell::~nsAppShell()
 void
 nsAppShell::NotifyNativeEvent()
 {
-    MutexAutoLock lock(mCondLock);
-    mQueueCond.Notify();
+    mEventQueue.Signal();
 }
 
 #define PREFNAME_COALESCE_TOUCHES "dom.event.touch.coalescing.enabled"
@@ -312,15 +310,6 @@ nsAppShell::Observe(nsISupports* aSubject,
     return NS_OK;
 }
 
-void
-nsAppShell::ScheduleNativeEventCallback()
-{
-    EVLOG("nsAppShell::ScheduleNativeEventCallback pth: %p thread: %p main: %d", (void*) pthread_self(), (void*) NS_GetCurrentThread(), NS_IsMainThread());
-
-    // this is valid to be called from any thread, so do so.
-    PostEvent(AndroidGeckoEvent::MakeNativePoke());
-}
-
 bool
 nsAppShell::ProcessNextNativeEvent(bool mayWait)
 {
@@ -818,34 +807,6 @@ nsAppShell::ResendLastResizeEvent(nsWindow* aDest) {
     }
 }
 
-AndroidGeckoEvent*
-nsAppShell::PopNextEvent()
-{
-    AndroidGeckoEvent *ae = nullptr;
-    MutexAutoLock lock(mQueueLock);
-    if (mEventQueue.Length()) {
-        ae = mEventQueue[0];
-        mEventQueue.RemoveElementAt(0);
-        if (mQueuedViewportEvent == ae) {
-            mQueuedViewportEvent = nullptr;
-        }
-    }
-
-    return ae;
-}
-
-AndroidGeckoEvent*
-nsAppShell::PeekNextEvent()
-{
-    AndroidGeckoEvent *ae = nullptr;
-    MutexAutoLock lock(mQueueLock);
-    if (mEventQueue.Length()) {
-        ae = mEventQueue[0];
-    }
-
-    return ae;
-}
-
 void
 nsAppShell::PostEvent(AndroidGeckoEvent *ae)
 {
@@ -921,11 +882,6 @@ nsAppShell::PostEvent(AndroidGeckoEvent *ae)
     NotifyNativeEvent();
 }
 
-void
-nsAppShell::OnResume()
-{
-}
-
 nsresult
 nsAppShell::AddObserver(const nsAString &aObserverKey, nsIObserver *aObserver)
 {