Properly throw java exceptions from shouldOverrideUrlLoading

base/message_loop/message_pump_android.cc

Index: base/message_loop/message_pump_android.cc
diff --git a/base/message_loop/message_pump_android.cc b/base/message_loop/message_pump_android.cc
index a0eee12c85c3034e9b42ec82d259e96619b06759..cbc4413faaa742181096927f5dcc767ad2d9504d 100644
--- a/base/message_loop/message_pump_android.cc
+++ b/base/message_loop/message_pump_android.cc
@@ -14,6 +14,7 @@
 #include "base/time/time.h"
 #include "jni/SystemMessageHandler_jni.h"
 
+using base::android::HasException;
 using base::android::ScopedJavaLocalRef;
 
 // ----------------------------------------------------------------------------
@@ -24,10 +25,14 @@ using base::android::ScopedJavaLocalRef;
 static void DoRunLoopOnce(JNIEnv* env,
                           const JavaParamRef<jobject>& obj,
                           jlong native_delegate,
+                          jlong native_message_pump,
                           jlong delayed_scheduled_time_ticks) {
   base::MessagePump::Delegate* delegate =
       reinterpret_cast<base::MessagePump::Delegate*>(native_delegate);
   DCHECK(delegate);
+  base::MessagePumpForUI* pump =
+      reinterpret_cast<base::MessagePumpForUI*>(native_message_pump);
+  DCHECK(pump);
   // This is based on MessagePumpForUI::DoRunLoop() from desktop.
   // Note however that our system queue is handled in the java side.
   // In desktop we inspect and process a single system message and then
@@ -35,6 +40,11 @@ static void DoRunLoopOnce(JNIEnv* env,
   // On Android, the java message queue may contain messages for other handlers
   // that will be processed before calling here again.
   bool did_work = delegate->DoWork();
+  if (pump->ShouldAbort()) {
+    // There is a pending JNI exception, return to Java so that the exception is
+    // thrown correctly
+    return;
+  }
 
   // In the java side, |SystemMessageHandler| keeps a single "delayed" message.
   // It's an expensive operation to |removeMessage| there, so this is optimized
@@ -60,6 +70,11 @@ static void DoRunLoopOnce(JNIEnv* env,
   // avoid comparisons with TimeDelta / Now() (expensive).
   base::TimeTicks next_delayed_work_time;
   did_work |= delegate->DoDelayedWork(&next_delayed_work_time);
+  if (pump->ShouldAbort()) {
+    // There is a pending JNI exception, return to Java so that the exception is
+    // thrown correctly
+    return;
+  }
 
   if (!next_delayed_work_time.is_null()) {
     // Schedule a new message if there's nothing already scheduled or there's a
@@ -85,9 +100,7 @@ static void DoRunLoopOnce(JNIEnv* env,
 
 namespace base {
 
-MessagePumpForUI::MessagePumpForUI()
-    : run_loop_(NULL) {
-}
+MessagePumpForUI::MessagePumpForUI() : run_loop_(NULL), should_abort_(false) {}

[danakj, 2016/07/20 21:37:08]

nit: nullptr while you're here?

[gsennton, 2016/07/26 14:42:39]

Done.

 
 MessagePumpForUI::~MessagePumpForUI() {
 }
@@ -109,9 +122,9 @@ void MessagePumpForUI::Start(Delegate* delegate) {
   JNIEnv* env = base::android::AttachCurrentThread();
   DCHECK(env);
 
-  system_message_handler_obj_.Reset(
-      Java_SystemMessageHandler_create(
-          env, reinterpret_cast<intptr_t>(delegate)));
+  system_message_handler_obj_.Reset(Java_SystemMessageHandler_create(
+      env, reinterpret_cast<intptr_t>(delegate),
+      reinterpret_cast<intptr_t>(this)));
 }
 
 void MessagePumpForUI::Quit() {
@@ -119,6 +132,7 @@ void MessagePumpForUI::Quit() {
     JNIEnv* env = base::android::AttachCurrentThread();
     DCHECK(env);
 
+    // We can't call back into java if there is a pending jni exception

[danakj, 2016/07/20 21:37:09]

I'm not sure what this comment means to explain, can you expand it? It also
doesnt end with a period, so maybe you left something off?

[Torne, 2016/07/21 13:38:25]

We need to avoid calling any Java functions (like this one) if we have a pending
Java exception already, because the VM will crash. Thus, we need to avoid the
Quit() codepath when trying to abort, because it calls back into Java.

I think this comment is incomplete/misplaced, it's not obvious what it means
here.

[gsennton, 2016/07/26 14:42:39]

Removed this comment since it doesn't really make any sense here.

     Java_SystemMessageHandler_removeAllPendingMessages(env,
         system_message_handler_obj_.obj());
     system_message_handler_obj_.Reset();