Reimplement finding form logic.

The previous implementation relied on autofill_agent finding forms, but
it is only interested in address and credit card forms. Instead, we call
the javascript function in CWVAutofillController to obtain all forms we
care about.

Also renamed delegate method from didFind to didScan since the former
implies that at least one was found but in many cases there are 0.

Bug: 905546
Change-Id: Ibb3144e767fe2257c20176d61315568cfde076cb
Reviewed-on: https://chromium-review.googlesource.com/c/1339322
Commit-Queue: John Wu <jzw@chromium.org>
Reviewed-by: Hiroshi Ichikawa <ichikawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609048}

ios/web_view/internal/autofill/cwv_autofill_controller.mm

@@ -6,6 +6,7 @@
 
 #include <memory>
 #include <string>
+#include <vector>
 
 #include "base/callback.h"
 #include "base/mac/foundation_util.h"
@@ -17,6 +18,7 @@
 #include "components/autofill/ios/browser/autofill_driver_ios.h"
 #include "components/autofill/ios/browser/autofill_driver_ios_bridge.h"
 #include "components/autofill/ios/browser/autofill_switches.h"
+#import "components/autofill/ios/browser/autofill_util.h"
 #import "components/autofill/ios/browser/js_autofill_manager.h"
 #import "components/autofill/ios/browser/js_suggestion_manager.h"
 #import "components/autofill/ios/form_util/form_activity_observer_bridge.h"
@@ -440,18 +442,7 @@ showUnmaskPromptForCard:(const autofill::CreditCard&)creditCard
 
 - (void)propagateAutofillPredictionsForForms:
     (const std::vector<autofill::FormStructure*>&)forms {
-  if (![_delegate respondsToSelector:@selector
-                  (autofillController:didFindAutofillableForms:)]) {
-    return;
-  }
-  NSMutableArray<CWVAutofillForm*>* autofillForms = [NSMutableArray array];
-  for (autofill::FormStructure* formStructure : forms) {
-    CWVAutofillForm* autofillForm =
-        [[CWVAutofillForm alloc] initWithFormStructure:*formStructure];
-    [autofillForms addObject:autofillForm];
-  }
-  [_delegate autofillController:self
-       didFindAutofillableForms:[autofillForms copy]];
+  // Not supported.
 }
 
 #pragma mark - AutofillDriverIOSBridge
@@ -474,6 +465,57 @@ showUnmaskPromptForCard:(const autofill::CreditCard&)creditCard
 
 #pragma mark - CRWWebStateObserver
 
+- (void)webState:(web::WebState*)webState didLoadPageWithSuccess:(BOOL)success {
+  if (!success) {
+    return;
+  }
+
+  // Find all forms in the page and notify |delegate|.
+  if (![_delegate respondsToSelector:@selector
+                  (autofillController:didScanForAutofillableForms:)]) {
+    return;
+  }
+
+  web::WebFramesManager* framesManager =
+      web::WebFramesManager::FromWebState(_webState);
+  DCHECK(framesManager);
+  web::WebFrame* webFrame = framesManager->GetMainWebFrame();
+  if (!webFrame) {
+    return;
+  }
+
+  GURL pageURL = _webState->GetLastCommittedURL();
+  GURL frameOrigin = webFrame->GetSecurityOrigin();
+  id completionHandler = ^(NSString* formJSON) {
+    std::vector<autofill::FormData> formDataVector;
+    bool success = autofill::ExtractFormsData(
+        formJSON, /*filtered=*/NO, /*form_name=*/base::string16(), pageURL,
+        frameOrigin, &formDataVector);
+    if (!success) {
+      return;
+    }
+    NSMutableArray<CWVAutofillForm*>* autofillForms = [NSMutableArray array];
+    for (const autofill::FormData& formData : formDataVector) {
+      autofill::FormStructure formStructure(formData);
+      formStructure.DetermineHeuristicTypes();
+      CWVAutofillForm* autofillForm =
+          [[CWVAutofillForm alloc] initWithFormStructure:formStructure];
+      if (autofillForm.type != CWVAutofillFormTypeUnknown) {
+        [autofillForms addObject:autofillForm];
+      }
+    }
+    [_delegate autofillController:self
+        didScanForAutofillableForms:[autofillForms copy]];
+  };
+
+  // Ignore empty forms.
+  NSUInteger minRequiredFieldsCount = 1;
+  [_JSAutofillManager
+      fetchFormsWithMinimumRequiredFieldsCount:minRequiredFieldsCount
+                                       inFrame:webFrame
+                             completionHandler:completionHandler];
+}
+
 - (void)webState:(web::WebState*)webState
     didRegisterFormActivity:(const autofill::FormActivityParams&)params
                     inFrame:(web::WebFrame*)frame {

ios/web_view/internal/web_view_web_main_parts.mm

@@ -52,10 +52,18 @@ void WebViewWebMainParts::PreCreateThreads() {
        switches::kSyncSupportSecondaryAccount.name,
        switches::kSyncUSSAutofillWalletData.name},
       ",");
+  std::string disabled_features = base::JoinString(
+      {// TODO(crbug.com/873790): Remove after supporting user consents.
+       switches::kSyncUserConsentSeparateType.name,
+       // Allows form_structure.cc to run heuristics on single field forms.
+       // This is needed to find autofillable password forms with less than 3
+       // fields in CWVAutofillControllerDelegate's
+       // |autofillController:didScanForAutofillableForms:| method.
+       autofill::features::kAutofillEnforceMinRequiredFieldsForHeuristics.name},
+      ",");
   feature_list->InitializeFromCommandLine(
       /*enable_features=*/enable_features,
-      // TODO(crbug.com/873790): Figure out if USER_CONSENTS need to be enabled.
-      /*disable_features=*/switches::kSyncUserConsentSeparateType.name);
+      /*disable_features=*/disabled_features);
   base::FeatureList::SetInstance(std::move(feature_list));
 #endif  // BUILDFLAG(IOS_WEB_VIEW_ENABLE_SYNC)
 }

ios/web_view/public/cwv_autofill_controller_delegate.h

@@ -47,8 +47,9 @@ typedef NS_ENUM(NSInteger, CWVPasswordUserDecision) {
 // Called to notify of all autofillable forms in the document after page load.
 // Autofillable forms are any form that has the potential to be autofilled
 // using a CWVAutofillSuggestion, regardless if any such suggestions exist yet.
+// Note that |forms| may be empty, indicating no forms were found.
 - (void)autofillController:(CWVAutofillController*)autofillController
-    didFindAutofillableForms:(NSArray<CWVAutofillForm*>*)forms;
+    didScanForAutofillableForms:(NSArray<CWVAutofillForm*>*)forms;
 
 // Called when a form field element receives a "focus" event.
 - (void)autofillController:(CWVAutofillController*)autofillController

ios/web_view/shell/shell_autofill_delegate.m

@@ -40,6 +40,11 @@
 
 #pragma mark - CWVAutofillControllerDelegate methods
 
+- (void)autofillController:(CWVAutofillController*)autofillController
+    didScanForAutofillableForms:(NSArray<CWVAutofillForm*>*)forms {
+  NSLog(@"%@ found %lu forms", NSStringFromSelector(_cmd), forms.count);
+}
+
 - (void)autofillController:(CWVAutofillController*)autofillController
     didFocusOnFieldWithIdentifier:(NSString*)fieldIdentifier
                         fieldType:(NSString*)fieldType