Make BlinkCloneableMessage and BlinkTransferableMessage move-only.

The mojo typemaps for BlinkCloneableMessage and BlinkTransferableMessage
specify that the structs are move-only, so the code in the mojo bindings
uses std::move. However, since the structs declare a custom constructor
(the constructor is defaulted in the .cpp, but the compiler can't see
this from the .h), no move constructor or move-assignment is generated,
and the structs are copied rather than being moved.

The mismatch causes extra reference increments / decrements. When the
underlying type uses thread-safe reference counter (like
SerializedScriptValue does), increments and decrements use atomic
operations, which are not cheap on ARM.

This CL adds move constructors and move-assignment operators to
BlinkCloneableMessage to allow moving, and adds DISALLOW_COPY_AND_ASSIGN
to prevent accidental copying.

This CL also adds DISALLOW_COPY_AND_ASSIGN to the browser-side
structures corresponding to Blink{Cloneable,Transferable}Message, to
make it obvious that they are move-only.

Bug: 794791
Change-Id: Iffe8f1e65bf9ccc2cd98082c341c2bdc3246fa33
Reviewed-on: https://chromium-review.googlesource.com/826260
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524085}

third_party/WebKit/Source/core/dom/BlinkCloneableMessage.cpp

@@ -9,4 +9,8 @@ namespace blink {
 BlinkCloneableMessage::BlinkCloneableMessage() = default;
 BlinkCloneableMessage::~BlinkCloneableMessage() = default;
 
+BlinkCloneableMessage::BlinkCloneableMessage(BlinkCloneableMessage&&) = default;
+BlinkCloneableMessage& BlinkCloneableMessage::operator=(
+    BlinkCloneableMessage&&) = default;
+
 }  // namespace blink

third_party/WebKit/Source/core/dom/BlinkCloneableMessage.h

@@ -5,6 +5,7 @@
 #ifndef BlinkCloneableMessage_h
 #define BlinkCloneableMessage_h
 
+#include "base/macros.h"
 #include "bindings/core/v8/serialization/SerializedScriptValue.h"
 #include "core/CoreExport.h"
 
@@ -18,7 +19,13 @@ struct CORE_EXPORT BlinkCloneableMessage {
   BlinkCloneableMessage();
   ~BlinkCloneableMessage();
 
+  BlinkCloneableMessage(BlinkCloneableMessage&&);
+  BlinkCloneableMessage& operator=(BlinkCloneableMessage&&);
+
   scoped_refptr<blink::SerializedScriptValue> message;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BlinkCloneableMessage);
 };
 
 }  // namespace blink

third_party/WebKit/Source/core/dom/BlinkTransferableMessage.cpp

@@ -9,4 +9,9 @@ namespace blink {
 BlinkTransferableMessage::BlinkTransferableMessage() = default;
 BlinkTransferableMessage::~BlinkTransferableMessage() = default;
 
+BlinkTransferableMessage::BlinkTransferableMessage(BlinkTransferableMessage&&) =
+    default;
+BlinkTransferableMessage& BlinkTransferableMessage::operator=(
+    BlinkTransferableMessage&&) = default;
+
 }  // namespace blink

third_party/WebKit/Source/core/dom/BlinkTransferableMessage.h

@@ -5,6 +5,7 @@
 #ifndef BlinkTransferableMessage_h
 #define BlinkTransferableMessage_h
 
+#include "base/macros.h"
 #include "bindings/core/v8/serialization/SerializedScriptValue.h"
 #include "core/CoreExport.h"
 #include "core/dom/BlinkCloneableMessage.h"
@@ -20,7 +21,13 @@ struct CORE_EXPORT BlinkTransferableMessage : BlinkCloneableMessage {
   BlinkTransferableMessage();
   ~BlinkTransferableMessage();
 
+  BlinkTransferableMessage(BlinkTransferableMessage&&);
+  BlinkTransferableMessage& operator=(BlinkTransferableMessage&&);
+
   Vector<MessagePortChannel> ports;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BlinkTransferableMessage);
 };
 
 }  // namespace blink

third_party/WebKit/common/message_port/cloneable_message.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/containers/span.h"
+#include "base/macros.h"
 #include "mojo/public/cpp/bindings/struct_ptr.h"
 #include "third_party/WebKit/common/common_export.h"
 
@@ -38,6 +39,9 @@ struct BLINK_COMMON_EXPORT CloneableMessage {
 
   // Blob handles for any blobs being sent in this message.
   std::vector<mojo::StructPtr<mojom::SerializedBlob>> blobs;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CloneableMessage);
 };
 
 }  // namespace blink

third_party/WebKit/common/message_port/transferable_message.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/containers/span.h"
+#include "base/macros.h"
 #include "third_party/WebKit/common/common_export.h"
 #include "third_party/WebKit/common/message_port/cloneable_message.h"
 #include "third_party/WebKit/common/message_port/message_port_channel.h"
@@ -24,6 +25,9 @@ struct BLINK_COMMON_EXPORT TransferableMessage : public CloneableMessage {
 
   // Any ports being transfered as part of this message.
   std::vector<MessagePortChannel> ports;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TransferableMessage);
 };
 
 }  // namespace blink