Add support for MimeHandlerViewInCrossProcessFrame (fixes issue #2727)

The PDF loading documentation in extension_system.cc has be updated to
describe the new code paths.

To support delivery of input events to the mime handler renderer process it is
now necessary to route events via the correct RWHV interface. For Aura-based
platforms (Windows/Linux) this means RWHVAura::On*Event and for macOS this
means RWHVMac::RouteOrProcess*Event. Since Aura uses UI event types these have
become the source of truth on Aura-based platforms with conversion to Web event
types when needed (primarily for OSR).

This change also adds a timeout for CefProcessHostMsg_GetNewBrowserInfo to
avoid a hung renderer process if the guest WebContents route is not
registered via CefMimeHandlerViewGuestDelegate::OnGuestDetached as expected
prior to CefBrowserInfoManager::OnGetNewBrowserInfo being called. This
timeout can be disabled for testing purposes by passing the
`--disable-new-browser-info-timeout` command-line flag.

The `--disable-features=MimeHandlerViewInCrossProcessFrame` command-line
flag can be used for a limited time to restore the previous implementation
based on BrowserPlugin. That implementation will be deleted starting with
the 3897 branch update.

Known issues:
- ExecuteJavaScript calls on the frame hosting the PDF extension will not
  be routed to the mime handler renderer process.
- The PDF extension will not load successfully if blocked by
  ChromePluginPlaceholder and then manually continued via the "Run this
  plugin" context menu option (see https://crbug.com/533069#c41).

patch/patches/mime_handler_view_guest_1565_2727.patch

@@ -1,21 +1,8 @@
 diff --git content/browser/browser_plugin/browser_plugin_guest.cc content/browser/browser_plugin/browser_plugin_guest.cc
-index 6eb21be63dec..87ccc46f4d43 100644
+index 6eb21be63dec..8617eff6bfc8 100644
 --- content/browser/browser_plugin/browser_plugin_guest.cc
 +++ content/browser/browser_plugin/browser_plugin_guest.cc
-@@ -306,8 +306,11 @@ void BrowserPluginGuest::InitInternal(
-           static_cast<WebContentsViewGuest*>(GetWebContents()->GetView());
-     }
- 
--    if (owner_web_contents_ && new_view)
-+    if (owner_web_contents_ && new_view) {
-       new_view->OnGuestDetached(owner_web_contents_->GetView());
-+      if (delegate_)
-+        delegate_->OnGuestDetached(owner_web_contents_->GetView());
-+    }
- 
-     // Once a BrowserPluginGuest has an embedder WebContents, it's considered to
-     // be attached.
-@@ -820,10 +823,19 @@ void BrowserPluginGuest::OnWillAttachComplete(
+@@ -820,7 +820,8 @@ void BrowserPluginGuest::OnWillAttachComplete(
          static_cast<WebContentsViewGuest*>(GetWebContents()->GetView());
      if (!web_contents()->GetRenderViewHost()->GetWidget()->GetView()) {
        web_contents_view->CreateViewForWidget(
@@ -25,17 +12,6 @@ index 6eb21be63dec..87ccc46f4d43 100644
      }
    }
  
-+  if (delegate_) {
-+    // Notify the delegate here instead of in InitInternal because InitInternal
-+    // will now be called from Init before GuestViewBase::CompleteInit has set
-+    // web_contents() to the guest WebContents. This behavior change is due to
-+    // https://crrev.com/07263b56.
-+    delegate_->OnGuestAttached(embedder_web_contents->GetView());
-+  }
-+
-   InitInternal(params, embedder_web_contents);
- 
-   attached_ = true;
 diff --git content/browser/frame_host/interstitial_page_impl.cc content/browser/frame_host/interstitial_page_impl.cc
 index 7bb71f92bb0a..a6b89a831044 100644
 --- content/browser/frame_host/interstitial_page_impl.cc
@@ -242,31 +218,8 @@ index 4721a9b3f511..dfdd46d0c5d2 100644
    RenderWidgetHostViewMac* view =
        g_create_render_widget_host_view
            ? g_create_render_widget_host_view(render_widget_host,
-diff --git content/public/browser/browser_plugin_guest_delegate.h content/public/browser/browser_plugin_guest_delegate.h
-index ea12af6b86b8..f1211f374328 100644
---- content/public/browser/browser_plugin_guest_delegate.h
-+++ content/public/browser/browser_plugin_guest_delegate.h
-@@ -20,6 +20,7 @@ class GuestHost;
- class RenderFrameHost;
- class RenderWidgetHost;
- class SiteInstance;
-+class WebContentsView;
- 
- // Objects implement this interface to get notified about changes in the guest
- // WebContents and to provide necessary functionality.
-@@ -68,6 +69,10 @@ class CONTENT_EXPORT BrowserPluginGuestDelegate {
-   // content module.
-   virtual void SetGuestHost(GuestHost* guest_host) {}
- 
-+  // Called when a guest is attached or detached.
-+  virtual void OnGuestAttached(content::WebContentsView* parent_view) {}
-+  virtual void OnGuestDetached(content::WebContentsView* parent_view) {}
-+
-   // TODO(ekaramad): A short workaround to force some types of guests to use
-   // a BrowserPlugin even when we are using cross process frames for guests. It
-   // should be removed after resolving https://crbug.com/642826).
 diff --git extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc
-index fa13ab856de9..ddc70aedbab2 100644
+index fa13ab856de9..81216c2bc8ff 100644
 --- extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc
 +++ extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc
 @@ -215,6 +215,8 @@ void MimeHandlerViewGuest::CreateWebContents(
@@ -278,42 +231,42 @@ index fa13ab856de9..ddc70aedbab2 100644
    // TODO(erikchen): Fix ownership semantics for guest views.
    // https://crbug.com/832879.
    std::move(callback).Run(
-@@ -259,6 +261,18 @@ bool MimeHandlerViewGuest::ShouldDestroyOnDetach() const {
+@@ -230,6 +232,9 @@ void MimeHandlerViewGuest::CreateWebContents(
+ }
+ 
+ void MimeHandlerViewGuest::DidAttachToEmbedder() {
++  if (delegate_)
++    delegate_->OnGuestAttached();
++
+   web_contents()->GetController().LoadURL(
+       stream_->handler_url(), content::Referrer(),
+       ui::PAGE_TRANSITION_AUTO_TOPLEVEL, std::string());
+@@ -259,6 +264,11 @@ bool MimeHandlerViewGuest::ShouldDestroyOnDetach() const {
    return true;
  }
  
-+void MimeHandlerViewGuest::OnGuestAttached(
-+    content::WebContentsView* parent_view) {
++void MimeHandlerViewGuest::WillDestroy() {
 +  if (delegate_)
-+    delegate_->OnGuestAttached(parent_view);
-+}
-+
-+void MimeHandlerViewGuest::OnGuestDetached(
-+    content::WebContentsView* parent_view) {
-+  if (delegate_)
-+    delegate_->OnGuestDetached(parent_view);
++    delegate_->OnGuestDetached();
 +}
 +
  WebContents* MimeHandlerViewGuest::OpenURLFromTab(
      WebContents* source,
      const content::OpenURLParams& params) {
 diff --git extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h
-index 3d0b70d06fe7..a33da99391f6 100644
+index 3d0b70d06fe7..06d5e5d4e9e3 100644
 --- extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h
 +++ extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h
-@@ -128,6 +128,10 @@ class MimeHandlerViewGuest
+@@ -127,6 +127,7 @@ class MimeHandlerViewGuest
+   void EmbedderFullscreenToggled(bool entered_fullscreen) final;
    bool ZoomPropagatesFromEmbedderToGuest() const final;
    bool ShouldDestroyOnDetach() const final;
++  void WillDestroy() override;
  
-+  // content::BrowserPluginGuestDelegate implementation
-+  void OnGuestAttached(content::WebContentsView* parent_view) override;
-+  void OnGuestDetached(content::WebContentsView* parent_view) override;
-+
    // WebContentsDelegate implementation.
    content::WebContents* OpenURLFromTab(
-       content::WebContents* source,
 diff --git extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h
-index 98689e261460..c501568b6f70 100644
+index 98689e261460..a1b08274f455 100644
 --- extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h
 +++ extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h
 @@ -8,9 +8,9 @@
@@ -336,8 +289,8 @@ index 98689e261460..c501568b6f70 100644
 +      content::WebContents::CreateParams* params) {}
 +
 +  // Called when a guest is attached or detached.
-+  virtual void OnGuestAttached(content::WebContentsView* parent_view) {}
-+  virtual void OnGuestDetached(content::WebContentsView* parent_view) {}
++  virtual void OnGuestAttached() {}
++  virtual void OnGuestDetached() {}
 +
    // Handles context menu, or returns false if unhandled.
    virtual bool HandleContextMenu(content::WebContents* web_contents,