[android] Resize the android_webview if it's 0x0 initially.

android_webview/common/render_view_messages.h

Index: android_webview/common/render_view_messages.h
diff --git a/android_webview/common/render_view_messages.h b/android_webview/common/render_view_messages.h
index f3c60db296ab392c8c4ef57a15a289b29cc574c2..6d4ce7d4d2deb611e2053877477bd3e3b77265a3 100644
--- a/android_webview/common/render_view_messages.h
+++ b/android_webview/common/render_view_messages.h
@@ -87,6 +87,10 @@ IPC_MESSAGE_ROUTED2(AwViewHostMsg_DocumentHasImagesResponse,
 IPC_MESSAGE_ROUTED1(AwViewHostMsg_UpdateHitTestData,
                     android_webview::AwHitTestData)
 
+// Sent whenever the page scale factor (as seen by RenderView) is changed.
+IPC_MESSAGE_ROUTED1(AwViewHostMsg_PageScaleFactorChanged,
+                    float /* page_scale_factor */)
+
 // Notification that a new picture becomes available. It is only sent if
 // AwViewMsg_EnableCapturePictureCallback was previously enabled.
 IPC_MESSAGE_ROUTED0(AwViewHostMsg_PictureUpdated)