[ppapi] Merged two identical interface_name

In jumbo build experiments, two cc files both defined
interface_name<PPB_InputEvent_1_0>() which clashed since in
jumbo builds many cc files are compiled in the same translation unit.

This moves the shared code to a shared file.

Bug: 898475
Change-Id: I9ce58e837d663cb5c15ba2596c22812a41def4c0
Reviewed-on: https://chromium-review.googlesource.com/c/1297148Reviewed-by: Bill Budge <bbudge@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Reviewed-by: Sam Clegg <sbc@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#607601}

native_client_sdk/src/libraries/ppapi_cpp/library.dsc

@@ -109,6 +109,7 @@
         'host_resolver.h',
         'image_data.h',
         'input_event.h',
+        'input_event_interface_name.h',
         'instance.h',
         'instance_handle.h',
         'logging.h',

ppapi/cpp/BUILD.gn

@@ -91,6 +91,7 @@ source_set("objects") {
     "image_data.h",
     "input_event.cc",
     "input_event.h",
+    "input_event_interface_name.h",
     "instance.cc",
     "instance.h",
     "instance_handle.cc",

ppapi/cpp/input_event.cc

@@ -4,6 +4,7 @@
 
 #include "ppapi/cpp/input_event.h"
 
+#include "ppapi/cpp/input_event_interface_name.h"
 #include "ppapi/cpp/instance_handle.h"
 #include "ppapi/cpp/module.h"
 #include "ppapi/cpp/module_impl.h"
@@ -15,10 +16,6 @@ namespace pp {
 
 namespace {
 
-template <> const char* interface_name<PPB_InputEvent_1_0>() {
-  return PPB_INPUT_EVENT_INTERFACE_1_0;
-}
-
 template <> const char* interface_name<PPB_KeyboardInputEvent_1_2>() {
   return PPB_KEYBOARD_INPUT_EVENT_INTERFACE_1_2;
 }

ppapi/cpp/input_event_interface_name.h

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_CPP_INPUT_EVENT_INTERFACE_NAME_H_
+#define PPAPI_CPP_INPUT_EVENT_INTERFACE_NAME_H_
+
+#include "ppapi/c/ppb_input_event.h"
+#include "ppapi/cpp/module_impl.h"
+
+namespace pp {
+
+namespace {
+
+// This implementation is shared between instance.cc and input_event.cc
+template <>
+const char* interface_name<PPB_InputEvent_1_0>() {
+  return PPB_INPUT_EVENT_INTERFACE_1_0;
+}
+
+}  // namespace
+}  // namespace pp
+
+#endif  // PPAPI_CPP_INPUT_EVENT_INTERFACE_NAME_H_

ppapi/cpp/instance.cc

@@ -14,6 +14,7 @@
 #include "ppapi/cpp/graphics_2d.h"
 #include "ppapi/cpp/graphics_3d.h"
 #include "ppapi/cpp/image_data.h"
+#include "ppapi/cpp/input_event_interface_name.h"
 #include "ppapi/cpp/instance_handle.h"
 #include "ppapi/cpp/logging.h"
 #include "ppapi/cpp/message_handler.h"
@@ -33,10 +34,6 @@ template <> const char* interface_name<PPB_Console_1_0>() {
   return PPB_CONSOLE_INTERFACE_1_0;
 }
 
-template <> const char* interface_name<PPB_InputEvent_1_0>() {
-  return PPB_INPUT_EVENT_INTERFACE_1_0;
-}
-
 template <> const char* interface_name<PPB_Instance_1_0>() {
   return PPB_INSTANCE_INTERFACE_1_0;
 }

ppapi/cpp/module_impl.h

@@ -17,9 +17,8 @@ namespace {
 
 // Specialize this function to return the interface string corresponding to the
 // PP?_XXX structure.
-template <typename T> const char* interface_name() {
-  return NULL;
-}
+template <typename T>
+const char* interface_name();
 
 template <typename T> inline T const* get_interface() {
   static T const* funcs = reinterpret_cast<T const*>(