Throw IOException at source of failing to open a dex file.

Before is:
java.lang.ClassNotFoundException: Didn't find class "GCBench" on path: DexPathList[[zip file "/disk2/dalvik-dev/out/host/linux-x86/framework/GCBench.jar"],nativeLibraryDirectories=[/disk2/dalvik-dev/out/host/linux-x86/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
        Suppressed: java.lang.ClassNotFoundException: GCBench
                at java.lang.Class.classForName(Native Method)
                at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
                at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
                at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
                ... 1 more
        Caused by: java.lang.NoClassDefFoundError: Class "LGCBench;" not found
                ... 5 more
And after is:
java.lang.ClassNotFoundException: Didn't find class "GCBench" on path: DexPathList[[zip file "/disk2/dalvik-dev/out/host/linux-x86/framework/GCBench.jar"],nativeLibraryDirectories=[/disk2/dalvik-dev/out/host/linux-x86/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
        Suppressed: java.io.IOException: Zip archive '/disk2/dalvik-dev/out/host/linux-x86/framework/GCBench.jar' doesn't contain classes.dex
                at dalvik.system.DexFile.openDexFile(Native Method)
                at dalvik.system.DexFile.<init>(DexFile.java:80)
                at dalvik.system.DexFile.<init>(DexFile.java:59)
                at dalvik.system.DexPathList.loadDexFile(DexPathList.java:268)
                at dalvik.system.DexPathList.makeDexElements(DexPathList.java:235)
                at dalvik.system.DexPathList.<init>(DexPathList.java:113)
                at dalvik.system.BaseDexClassLoader.<init>(BaseDexClassLoader.java:48)
                at dalvik.system.PathClassLoader.<init>(PathClassLoader.java:38)
                at java.lang.ClassLoader.createSystemClassLoader(ClassLoader.java:128)
                at java.lang.ClassLoader.access$000(ClassLoader.java:65)
                at java.lang.ClassLoader$SystemClassLoader.<clinit>(ClassLoader.java:81)
                at java.lang.ClassLoader.getSystemClassLoader(ClassLoader.java:137)
        Suppressed: java.lang.ClassNotFoundException: GCBench
                at java.lang.Class.classForName(Native Method)
                at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
                at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
                at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
                ... 1 more
        Caused by: java.lang.NoClassDefFoundError: Class "LGCBench;" not found
                ... 5 more

Also, move dex file verifier messages out of logs.
In the process the ClassLinker::dex_lock_ needed tidying to cover a smaller
scope. Bug 11301553.

Change-Id: I80058652e11e7ea63457cc01a0cb48afe1c15543
diff --git a/compiler/oat_test.cc b/compiler/oat_test.cc
index 6ac5d6a..634a160 100644
--- a/compiler/oat_test.cc
+++ b/compiler/oat_test.cc
@@ -100,8 +100,10 @@
     base::TimingLogger timings("CommonTest::WriteRead", false, false);
     compiler_driver_->CompileAll(class_loader, class_linker->GetBootClassPath(), timings);
   }
-  UniquePtr<OatFile> oat_file(OatFile::Open(tmp.GetFilename(), tmp.GetFilename(), NULL, false));
-  ASSERT_TRUE(oat_file.get() != NULL);
+  std::string error_msg;
+  UniquePtr<OatFile> oat_file(OatFile::Open(tmp.GetFilename(), tmp.GetFilename(), NULL, false,
+                                            &error_msg));
+  ASSERT_TRUE(oat_file.get() != nullptr) << error_msg;
   const OatHeader& oat_header = oat_file->GetOatHeader();
   ASSERT_TRUE(oat_header.IsValid());
   ASSERT_EQ(1U, oat_header.GetDexFileCount());  // core
@@ -111,8 +113,9 @@
 
   const DexFile* dex_file = java_lang_dex_file_;
   uint32_t dex_file_checksum = dex_file->GetLocationChecksum();
-  const OatFile::OatDexFile* oat_dex_file = oat_file->GetOatDexFile(dex_file->GetLocation(),
+  const OatFile::OatDexFile* oat_dex_file = oat_file->GetOatDexFile(dex_file->GetLocation().c_str(),
                                                                     &dex_file_checksum);
+  ASSERT_TRUE(oat_dex_file != nullptr);
   CHECK_EQ(dex_file->GetLocationChecksum(), oat_dex_file->GetDexFileLocationChecksum());
   for (size_t i = 0; i < dex_file->NumClassDefs(); i++) {
     const DexFile::ClassDef& class_def = dex_file->GetClassDef(i);