android: Add CHECK() calls to better understand memory corruption.

base/android/jni_android.cc

Index: base/android/jni_android.cc
diff --git a/base/android/jni_android.cc b/base/android/jni_android.cc
index 59f25e2e817dbe6ea258d16b65b7d71e5bedb9ec..c9cdf0dd16eaeab775a8bc7b296ee4bd2f4b9e51 100644
--- a/base/android/jni_android.cc
+++ b/base/android/jni_android.cc
@@ -17,6 +17,8 @@ using base::android::MethodID;
 using base::android::ScopedJavaLocalRef;
 
 JavaVM* g_jvm = NULL;
+const JNIInvokeInterface* g_jvm_functions = NULL;

[joth, 2013/11/25 17:08:42]

Is the layout of JNIInvokeInterface guaranteed to be consistent across platform
versions?

FWIW I'd put the comment here that this variable, and all usage of it, is for
debugging crbug/xxx

[digit1, 2013/11/25 17:34:02]

Yes, since the structure is defined in <jni.h>, its layout must be stable to
avoid breaking generated machine code.

I'll add some comments though.

[digit1, 2013/11/25 17:35:53]

Done.

+
 // Leak the global app context, as it is used from a non-joinable worker thread
 // that may still be running at shutdown. There is no harm in doing this.
 base::LazyInstance<base::android::ScopedJavaGlobalRef<jobject> >::Leaky
@@ -76,7 +78,10 @@ namespace android {
 JNIEnv* AttachCurrentThread() {
   DCHECK(g_jvm);
   JNIEnv* env = NULL;
-  jint ret = g_jvm->AttachCurrentThread(&env, NULL);
+  // See http://crbug.com/322200 for the reasons for these CHECKs.
+  CHECK(g_jvm);
+  CHECK_EQ(g_jvm_functions, g_jvm->functions);
+  jint ret = g_jvm_functions->AttachCurrentThread(g_jvm, &env, NULL);
   DCHECK_EQ(JNI_OK, ret);
   return env;
 }
@@ -84,13 +89,18 @@ JNIEnv* AttachCurrentThread() {
 void DetachFromVM() {
   // Ignore the return value, if the thread is not attached, DetachCurrentThread
   // will fail. But it is ok as the native thread may never be attached.
-  if (g_jvm)
+  if (g_jvm) {
+    // See http://crbug.com/322200 for the reasons for these CHECKs.
+    CHECK(g_jvm);
+    CHECK_EQ(g_jvm_functions, g_jvm->functions);
     g_jvm->DetachCurrentThread();
+  }
 }
 
 void InitVM(JavaVM* vm) {
   DCHECK(!g_jvm);
   g_jvm = vm;
+  g_jvm_functions = vm->functions;
 }
 
 bool IsVMInitialized() {