base: inline ThreadSafeRefCounted destructor in release builds.

For some reason, the ThreadSafeRefCounted destructor was not
inlined in release builds. The end result was a completely empty
function, that was called in many many places.

This tells the compiler that, for release build, the destructor
is inlined and doesn't do anything. This tiny patch reduces the
final (compressed) size of the following Android APKs:

  - Chrome.apk       -60 KiB  (from 45 MiB)
  - Monochrone.apk  -152 KiB  (from 69 MiB)

Note that the destructor is kept non-inlined for debug builds,
since it must perform relevant debug checks.

R=tzik@chromium.org,thakis@chromium.org,dcheng@chromium.org,agrieves@chromium.org
BUG=NONE

Change-Id: I45c9e87851a3c71861034bde8906b59d1033c455
Reviewed-on: https://chromium-review.googlesource.com/702301Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Taiju Tsuiki <tzik@chromium.org>
Commit-Queue: David Turner <digit@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506786}

base/memory/ref_counted.cc

@@ -21,12 +21,12 @@ bool RefCountedThreadSafeBase::HasOneRef() const {
   return ref_count_.IsOne();
 }
 
-RefCountedThreadSafeBase::~RefCountedThreadSafeBase() {
 #if DCHECK_IS_ON()
+RefCountedThreadSafeBase::~RefCountedThreadSafeBase() {
   DCHECK(in_dtor_) << "RefCountedThreadSafe object deleted without "
                       "calling Release()";
-#endif
 }
+#endif
 
 #if defined(ARCH_CPU_64_BIT)
 void RefCountedBase::AddRefImpl() const {

base/memory/ref_counted.h

@@ -167,7 +167,11 @@ class BASE_EXPORT RefCountedThreadSafeBase {
 #endif
   }
 
+#if DCHECK_IS_ON()
   ~RefCountedThreadSafeBase();
+#else
+  ~RefCountedThreadSafeBase() = default;
+#endif
 
 // Release and AddRef are suitable for inlining on X86 because they generate
 // very small code sequences. On other platforms (ARM), it causes a size